NIDA for Teens: The Science Behind Drug Abuse
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  • The NIDA Blog Team

    This is the final post of a 3-part series on the science of medical marijuana. Check out Part 1: What’s Wrong with “Medical Marijuana”? and Part 2: Making Medicine from Marijuana.

    People who write about the health benefits of marijuana sometimes think it’s ironic that a plant containing compounds that could treat disease (like THC or CBD) is banned by the government for being unsafe. But in fact many effective, FDA-approved medicines are closely related to illegal, harmful drugs and are sometimes even made from the same sources.

    That’s because there’s a fine (and sometimes fuzzy) line between chemicals that are good for you and those that can hurt or even kill you. In fact, the Greek word pharmakon, where we get pharmacy, originally meant both “medicine” and “poison.”

    Speaking the Body’s Language

    The opium poppy is a great example. It’s the source of a drug called morphine, part of a class of drugs called opioids.  Morphine is used to make heroin—a very addictive and sometimes deadly drug. But it is also modified and used to make many effective, relatively safe pain relievers prescribed widely by doctors and dentists. In fact, these opioids are our most valuable drugs for pain relief.

    Another example is cocaine, from the coca plant. It is part of a class of drugs called stimulants. Cocaine is an especially dangerous, addictive stimulant, but it is closely related to medications used to treat people with attention deficit hyperactivity disorder (ADHD) and other conditions. It is also used sometimes as an anesthetic.

    The thing that makes a drug a drug is the ability to speak the body’s language—specifically, to interact with one of the many chemical signaling systems that cells use to talk to each other. Both heroin and cocaine are able to do that, fluently.

    Same with marijuana: Its cannabinoid chemicals speak the body’s own endocannabinoid language.

    Parlez-Vous Endocannabinoid?

    Nerve cells use chemicals called neurotransmitters to send each other messages, and there are several different kinds of neurotransmitters. Similar chemicals in plants or in foods can interact with these neurotransmitter systems because their molecules are very similar to the ones produced naturally in the human body.

    Morphine from the poppy plant is able to work in your nervous system because it closely resembles your body’s own natural pain-relieving opioid chemicals—the endorphins that cause a “runner’s high.” (The “endo” in endorphin or endocannabinoid means “from inside”—that is, inside your body.)

    Cocaine and related stimulants work with your own neurotransmitter dopamine, which naturally keeps you focused on rewarding activities.

    And the THC in marijuana interacts with the endocannabinoid signaling system used by the body’s own cannabinoid chemicals—such as anandamide—in brain circuits that control a wide range of things including pleasure, memory, thinking, concentration, movement, coordination, and even how you perceive time. That’s why THC is able to interfere with these abilities when people smoke marijuana either to get high or to treat a medical condition.

    The endocannabinoid system also is involved in things like appetite and pain, which is why THC has been made into an effective medication for helping treat nausea and loss of appetite in AIDS and cancer-chemotherapy patients.  And it is why it may, in the future, be prescribed for treating pain as well.

    So, there’s nothing special about marijuana: It’s one of many plants that contain substances that can be both beneficial and harmful, depending on how they are used.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    How much do you really know about why people become addicted to drugs, whether marijuana can be medicine, and what causes a hangover?

    Every January, the National Institute on Drug Abuse (NIDA) hosts a chat day for National Drug and Alcohol Facts WeekSM (NDAFW). This year, NIDA scientists answered more than 1,600 questions from teens and others about drug and alcohol use. Here are a few of our favorites from this year’s questions; a link to the full chat transcript is on our NDAFW page.

    1. Why do some people become addicted, while others don’t?

    Great question, and a hard one. We don’t fully understand yet why this is so. We know that genes play a part, because an inclination for addiction can run in families, and because different strains of mice, rats, and other animals differ in how readily they develop addiction-like behaviors after they’re exposed to drugs. We also know that a person’s environment plays a part in addiction. For example, what are the factors that encourage someone who has tried a drug to keep on taking it to the point where they can’t stop? Many scientists are trying to untangle the answers so that we can find better ways to prevent and treat addiction. See these videos on how anyone can become addicted, and why drugs are so hard to quit.

    2. What can cause a hangover?

    There are several reasons why people experience hangovers from drinking. One component is dehydration. Alcohol causes the body to get rid of too much fluid, and the dehydration that results can cause headaches, nausea, thirst, and other symptoms of hangovers. While some people think that alcohol helps a person sleep, it actually disrupts sleep, and that can contribute to the grogginess that accompanies hangovers. 

    3. What properties in drugs make them addicting?

    Different drugs act on the brain in different ways, but they all cause release of the neurotransmitter dopamine in the brain’s reward area, which is what causes the pleasurable sensation (the high). Once a person uses a drug repeatedly, their brain starts to adjust to these surges of dopamine; the brain cells (neurons) make fewer dopamine receptors, or they simply produce less dopamine. The result is a lower amount of “dopamine signaling” in the reward area—it’s like “turning down the volume” on the reward signal. Then the person may start to find natural “rewards”—like food, relationships, or sex—less pleasurable; that’s one of the signs of addiction. Also, reduced dopamine signaling in the brain’s prefrontal cortex, which governs our ability to inhibit (slow down or stop) our impulses, makes it harder to resist the urge to take drugs even if a person would like to quit. Learn more about how drugs affect your brain and body.

    4. Does marijuana use lead to the use of other drugs?

    The “gateway drug” concept—where using one drug leads a person to use other drugs— generates a lot of controversy. Researchers haven’t found a definite answer yet, but as of today the research does suggest that, while most people who smoke marijuana do not go on to use other drugs, most teens who do use other illegal drugs try marijuana first. For example, the risk of using cocaine is much greater for those who have tried marijuana than for those who have never tried it. However, this risk is also greater for people who have used alcohol and tobacco. Animal studies suggest that because the teen brain is still developing, using marijuana, alcohol, or tobacco in your teen years (or earlier) may alter your brain’s reward system (see the answer to #3 above), and that may put teens at higher risk of using other drugs. In addition, using marijuana puts children and teens in contact with people who use and sell other drugs, increasing the risk of additional drug use.

    5. Is medical marijuana good for you?

    The marijuana plant has not been approved by the FDA for the treatment of any medical condition. A pill form of THC (the main chemical in marijuana that affects the brain) is already available for certain conditions, such as nausea associated with cancer chemotherapy and weight loss in patients with AIDS. Early research suggests that some of the active ingredients in marijuana, like THC and cannabidiol (CBD), might be able to help treat conditions and diseases like epilepsy, cancer, or addiction. Scientists are studying THC and CBD to try to develop new medications. However, smoked marijuana is unlikely to be an ideal medication because of its negative health effects, including the risk of addiction and the damage that smoking can do to your lungs.

    6. Can drugs affect animals?

    Yes. Chemicals can have different effects in different animals—for instance, chocolate is delicious to humans and poisonous to dogs—so even small amounts of a drug could be very harmful for your pet. Alcohol can cause a dog to suffer dangerous drops in blood pressure, blood sugar, and body temperature, to have seizures, and to stop breathing. In dogs and cats poisoned by marijuana, signs may be seen within 3 hours, such as a lack of energy, low heart rate, low blood pressure, respiratory depression, hyperactivity, seizures, vomiting, and coma. Also, your pet wouldn’t understand that it had been given a drug, and the sensations that might feel like a “high” to a human would be a very scary experience for an animal.

    7. How can I help someone if they are on drugs?

    One of the best things you can do for a friend with a serious drug problem is let them know you are there to support them. Tell them you’re concerned about their drug use and encourage them to seek help from a trusted adult; maybe a teacher, coach, parent, or counselor can help. You can also help by being a strong positive influence; help them get involved in non-drug-using activities like joining a club, playing music, or playing a sport. However, if your friend is becoming a negative influence in your life, you might have to step away from the friendship for a while. If you feel your friend is a danger to himself or herself, or to others, it is important to tell a trusted adult right away; it could save your friend’s life. To get them help, go to

    8. Are video games more addictive than drugs?

    No, they aren’t more addictive—for example, they don’t cause painful physical withdrawal when you stop. Technically, video games wouldn’t be considered addictive. But they do act on some of the same systems in the brain as addictive drugs. For instance, they produce bursts of dopamine (described in answer #3 above), and some people think that playing video games a lot might cause problems similar to drug use, such as being unable to get satisfaction from other things in life. 

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Marijuana is the dried leaves and flowers of the hemp plant (Cannabis sativa). Like all plants it's sensitive to the environment where it grows.

    Different weather and soil conditions can change the amounts of the chemicals inside the plant. That means marijuana grown in a place like Hawaii might be chemically different than marijuana from Mexico or vice-versa.

    How does marijuana affect nerve cells in the brain?

  • The NIDA Blog Team

    With so much hype about marijuana legalization and the “drug war,” it’s easy to think that marijuana is just a modern phenomenon (or invented by the hippies). But the cannabis (or hemp) plant has had a long—really long!—history. And while the plant, and the way it is used, has changed a lot over the centuries, it’s interesting to take the long view of marijuana and look back at its history. For this three-part series, we’ll be your tour guide of cannabis through the ages.

    Starting in Asia…

    The cannabis or hemp plant (which only came to be called marijuana in the 20th century) has a long history, going back several thousand years—first in Central Asia, then spreading east to China, south to India, and westward to Europe, the Middle East, and Africa.

    In most ancient cultures, though, “getting high” was not the main use for the plant. Hemp fiber was valued for making clothes and other textiles, and its seeds were used for food and oil. The types of plant used for these purposes had very low amounts of THC, the chemical that causes intoxication.

    The ancients did know, however, about the plant’s mind-altering properties and may have bred varieties for this purpose as well. The oldest evidence of this is the remains of burned cannabis seeds that have been found in graves of shamans—religious leaders and healers—in China and Siberia from around 500 BC.

    Ancient “Medical Marijuana”

    Shamans enlisted the aid of spirits to help their community and try to cure sickness. Sometimes this was done with the help of intoxicating substances, and it is likely that cannabis was used this way. It probably wasn’t “recreational” but was believed to be a serious religious and healing tool to be respected.

    We now know that THC can be used medically to treat nausea—in fact, two FDA-approved drugs with THC are prescribed in pill form to people who feel sick or have no appetite as a result of chemotherapy or AIDS. The ancients seem to have used cannabis to treat similar ailments. It appears in ancient medical texts from ancient Egypt, and ancient Greek physicians described using it for stomach problems.

    Cannabis as a Recreational Drug

    The oldest evidence of marijuana being used recreationally comes from an ancient Greek historian named Herodotus (484–425 BC). He described how people of a Eurasian society called the Scythians inhaled the vapor of cannabis seeds and flowers thrown on heated rocks. It might have not sounded that appealing to his Greek readers, though, who much preferred to get “high” on wine, as did the Romans later.

    The first drug to rival alcohol for popularity in Europe was tobacco, imported from America in the late 1500s. Coffee followed about a century later, imported from Africa. And although Europeans cultivated hemp and occasionally smoked cannabis, its popularity didn’t match that of alcohol, tobacco, and coffee.

    Unlike in Europe, however, cannabis (in the concentrated form called hashish) did become widely used in the Middle East and South Asia after about 800 AD. The reason has to do with the spread of Islam. The Koran strictly forbade Muslims from drinking alcohol or partaking in other intoxicating substances, but it did not specifically mention cannabis. Cannabis is prohibited in most Islamic countries today, though, as it is throughout much of the world.

    Part 2 of this series gives a brief history of cannabis in America and answers the question: Did the Founding Fathers really smoke it, as rumors have claimed?

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Clara Mente buceando en el cerebro

    ¿De qué manera las sustancias químicas de la marihuana cambian la forma en que una persona ve, oye, huele, gusta y siente las cosas?

  • Brochure, in question-and-answer format, that provides facts about marijuana for parents and offers tips for talking with their children about the drug and its potential harmful effects.

  • The NIDA Blog Team

    Marijuana has long been seen as an “alternative” drug. It was illegal for everyone, and those who used it regularly were seen as “stoners” or “hippies” or “partiers” and were somehow different than “regular” people. There was a stereotype of people who used marijuana and most people didn’t think much about it.

    And then came the rise of medical marijuana, and that began to change marijuana’s reputation. It was seen, by some, as medicine, and in some states people were able to get a prescription for it and use it to help them with specific health problems. Marijuana started to change its image. Now, along with the typical marijuana user, there were people who had medical conditions enabling them to get a prescription and use marijuana legally.

    But the biggest change in marijuana’s image is what has happened in two states, Colorado and Washington, where marijuana has been made legal for adults to use, with or without a prescription. This change pushed marijuana out of the shadows and into the spotlight.

    Marijuana is still not as popular as alcohol or tobacco in those states, but this new identity as a “legal drug” has come with a change in perception that marijuana is safe, and that the reasons it was illegal before no longer exist.

    This really worries people who dedicate their lives to the health of the public. That’s especially true when it comes to people who care about teens, whose brains are actively developing and may really be damaged by marijuana use.

    Colorado is working to counter the effects of marijuana’s image makeover by constructing human-sized rat cages to raise awareness about the effects of marijuana on young people, getting the point across that using it as a teenager is kind of like doing an experiment on your brain. Thus the campaign’s message: “Don’t be a lab rat” and questions like “Can marijuana really cause schizophrenia in teenagers? Volunteers, anyone?” The cages are displayed in places popular with kids and teens, such as a skate park and the public library.

    Tell us in comments: Do you think advertising campaigns can help teens see that marijuana is still dangerous for them to use?

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    This is the second part of an update to the post, “Using Drugs When Pregnant Harms the Baby.”

    Last week we described some of the recent scientific research about the dangers to an unborn baby’s health if the baby’s mother smokes or vapes while she’s pregnant. Now let’s look at recent discoveries about how a pregnant woman’s use of marijuana, opioids, or other drugs can affect her baby.

    Weed and pregnancy don’t mix

    You’ve probably heard that marijuana can affect a teen’s brain, which is still developing. Well, think of how it might affect a tiny baby’s brain. The active ingredient in marijuana, THC, may affect the way a baby’s brain grows and develops. A recent study found that if a pregnant mouse is exposed to marijuana, the baby mice have difficulty with solving problems, paying attention, remembering information, and socializing. The reasons aren’t clear yet, but it’s possible that THC is affecting the development of the brain cells (or neurons) that are important to those skills and behaviors.

    Another study found that pregnant women who smoke marijuana may triple their risk for a stillbirth (a baby who dies after 20 weeks or more in the womb).

    Research also discovered that using marijuana in pregnancy is associated with a 77 percent higher risk for having a baby with a low birth weight—which sometimes results in health problems such as sickness early in life or long-term learning disabilities—and can double the risk of a baby being placed in intensive care.

    These studies didn’t show that using marijuana while pregnant directly caused stillbirths and low birth weight; more research is needed to see exactly what’s behind the connection. For now, it’s important for expectant mothers to know about the significantly higher health risks associated with marijuana use.

    Pain reliever misuse = pregnancy problems

    The dramatic increase in the misuse of prescription opioid pain relievers in the last several years has brought new attention to the dangers of using them while pregnant. Researchers have found that a pregnant woman’s use of opioids can lead to neonatal abstinence syndrome (NAS), where the baby becomes dependent on the drug just as the mother does. It can also bring a higher risk for the baby to have heart defects, spine problems, and buildup of fluid in the brain (hydrocephalus).

    Other drugs: not for babies, either

    An expecting mother’s use of other kinds of drugs has all kinds of risks for the baby.

    For instance, using cocaine can lead to premature birth, low birth weight, and NAS. A pregnant woman who uses heroin has an increased risk of miscarrying, having a baby of low birth weight, and NAS.

    And let’s not forget alcohol, which can cause brain damage in an unborn child, leading to problems with development, thinking ability, and behavior.

    If you’re pregnant and you smoke, drink alcohol, or use drugs, you can get help—and help your baby in the process. Your doctor can recommend programs to help you quit, or you can call 1-800-662-HELP (4357), the Helpline of the Substance Abuse and Mental Health Services Administration (SAMHSA); visit SAMHSA’s online treatment locators; or use SAMHSA’s Step-by-Step Guides.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • How do the chemicals in marijuana change the way a person sees, hears, smells, tastes, and feels things?

    When someone uses marijuana, these chemicals travel through the bloodstream and quickly attach to special places on the brain's nerve cells. These places are called receptors, because they receive information from other nerve cells. Chemicals carry this information, which changes the nerve cell receiving it.

  • The NIDA Blog Team

    Recently, the NIDA Blog Team brought the science of marijuana to life in a series of posts about the drug’s effects on your brain, perception, pets, driving, and more. Here are a few highlights!

    1. Marijuana use interferes with attention, motivation, memory, and learning. When used heavily during the teen years, it can lower grades and your IQ

    A young man looking dumbfounded.


    2.  Exposure to secondhand marijuana smoke rarely results in a contact high.

    A man looking relieved.


    3. Serving sizes for marijuana edibles are confusing—it’s easy to eat much more than a person means to, with bad side effects. 

    A women looking surprised as she is about to bite a piece of chocolate.

    For real?

    4. Marijuana doesn’t make you more creative—it just makes you think you are.

    A dog with a beret, holding a painter's palette.

    Dude, this is my masterpiece.

    5. Marijuana can make dogs ill, causing serious medical issues such as injury, dehydration, anxiety, lethargy, impaired balance, vomiting, or diarrhea. A few have even died from eating it.

    A sad-looking puppy.

    No bueno.

    6. Drugged driving is dangerous, illegal, and happening more and more. The risk of being in an accident doubles after marijuana use.

    A police officer writing a ticket.

    Do you know why I pulled you over?

    7. Over three-quarters of the students surveyed in the Monitoring the Future study (and four-fifths of 8th graders) said they disapproved of people using marijuana regularly.

    A teen girl looking disappointed.

    Do better.

    8. Spice, also known as K2, is not fake marijuana. In fact, some effects of Spice are much more intense than those of marijuana and have even been linked to deaths.

    A teen boy looking surprised.


    9. A small number of medications that contain THC are approved by the Food and Drug Administration. They are used for treating nausea and appetite problems caused by cancer chemotherapy and AIDS. Marijuana’s other chemical—cannabidiol or CBD—also is being studied for potential medical uses, including treatment for seizures.

    A young girl dressed as a scientist.


    10. Ancient healers used cannabis in religious ceremonies—not as a party drug.

    Cannabis plant.

    That’s old school.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  •  foto del con hipopótamo

    Una región del cerebro que contiene muchos receptores de THC es el hipocampo, que es donde se procesa la memoria. Cuando el THC se adhiere a los receptores en el hipocampo, debilita la memoria de corto plazo.

  • Offers facts about marijuana, including how people use it, its effects on the brain and overall health, and treatment options.

  • The NIDA Blog Team

    You already know the dangers of using marijuana before driving: Marijuana seriously impairs your motor skills and clouds your perception and judgment, all of which you need to safely operate a car. That’s why it’s illegal to drive high. But lots of people don’t know this … or they know it, but figure it’s okay “just this one time.” Whatever the case, it’s breaking the law, just like driving after drinking alcohol.

    Driving under the influence of marijuana is a big problem. A 2007 study by the National Highway Transportation Safety Administration found that 8.7 percent of people driving at night on a weekend had been using marijuana—4 times the percentage of drivers who had had enough alcohol to impair them.

    With all of these drugged drivers, police need an easy test to check if people have been using marijuana, like they have for alcohol. Unfortunately, there isn’t one—yet.

    A Marijuana Breathalyzer

    With alcohol, police can test a driver’s breath and tell if the person has enough in their system to impair their driving—a device called a breathalyzer. This works because alcohol leaves the body quickly.  This also means that the breathalyzer only measures alcohol that has been recently used.

    Measuring marijuana, however, turns out to be way, way more complicated.

    For one thing, marijuana can stick around in a person’s body a lot longer than alcohol. It can be detected in blood tests of heavy users as much as a month after they’ve stopped using it! So in theory, heavy marijuana users could test positive in a blood test for marijuana even if they haven’t used it in a few weeks.

    Another tricky thing with marijuana is that, after taking it, frequent users may show a higher amount of THC (marijuana’s active ingredient) in their body fluids than infrequent users do, even if the effect on their driving abilities is similar.

    This means there’s a big need for a test that can universally tell when a person has consumed marijuana during the previous few hours, when it can have its biggest impact on driving ability—whether or not he or she uses the drug frequently or just occasionally. It also needs to be easy to use by police and painless for drivers.

    Scientists are hard at work on the problem, and last fall a team of researchers at NIDA’s Intramural Research Program had a breakthrough: a first successful test of a marijuana breathalyzer.

    Getting High for Science

    In their research study, the scientists had a group of frequent marijuana-using adults and a comparison group of occasional marijuana-using adults each smoke a single marijuana cigarette (with an exactly measured dose of THC) and then provide breath samples using a device called SensAbues. Both groups tested positive up to an hour later, and frequent users tested positive 2 hours later.

    So far it’s not perfect, and even though the collection device is very portable, the equipment to test the results isn’t, so there are still some hurdles. But it’s one step closer to making the roads safer from drugged drivers.

    Tell us what you think in comments: Do you think if the police had a marijuana breath test, it would deter people from using marijuana before driving?

    Check out these PSAs from Colorado reminding residents that while recreational use of marijuana is legal—driving under the influence of marijuana is illegal.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • One region of the brain that contains a lot of THC receptors is the hippocampus, which usually helps with memory. When THC attaches to receptors in the hippocampus, it interferes with memory.

    Researchers have also shown that heavy use of marijuana by young people can actually cause IQ to go down—and this change in IQ can last a long time and may even be permanent! This means that someone who uses marijuana may not do as well in school and may have trouble remembering things like their friend's phone number.

  • The NIDA Blog Team

    In Part 1, we showed how the cannabis (hemp) plant spread from Asia to other parts of the world thousands of years ago, mainly because of its usefulness as a fiber and a grain. But as in ancient times, today some people used it for healing and some used it as a recreational drug. Now we’ll look at cannabis in America from Colonial times until the start of the 20th century, and lay to rest one of the biggest myths about the history of this drug.

    Did the Founding Fathers Smoke It?

    The cannabis or hemp plant has been an important source of grain and fiber for thousands of years. It was brought to North and South America by European colonists in the 1500s. Hemp fiber was widely used for making sails, rope, clothing, paper, and other valuable commodities, and the growing of hemp was encouraged by the American colonies.

    There is a popular story you might have heard that the Founding Fathers of our nation smoked hemp. You might even see Thomas Jefferson quoted as saying: "Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see."

    In fact, that quote is completely made up. None of his writings include it (or anything like it); it was falsely attributed to him—no doubt by a marijuana fan—in recent times, and it has lived a life of its own on the Internet along with lots of other made-up “facts.”

    Jefferson, along with George Washington and Benjamin Franklin, did grow hemp on their farms, as did most people who owned land, but there’s no direct evidence they ever smoked it. The amount of the psychoactive (mind-altering) chemical THC in most hemp at the time was probably too low anyway to become intoxicated from it. When Colonial Americans smoked anything, it was mainly tobacco—the drug that was also a big part of America’s economy during those times.

    Cannabis From the Druggist

    Cannabis was not widely used recreationally in the United States until the 20th century, but in the 1800s it was used as a medicine. In the 1830s, an Irish doctor in India found that cannabis extracts (not the smoked kind) could lessen the terrible vomiting of people suffering from the often fatal disease cholera. His discovery spread, and by the late 1800s, cannabis extracts were commonly sold by American druggists (pharmacists) for ailments, including stomach problems.

    Using cannabis extracts to treat digestive symptoms makes some sense, scientifically. We now know that THC is able to lessen nausea, as well as promote hunger, by interacting with areas of the brain that regulate those functions, like the brainstem and hypothalamus. Today, two FDA- approved THC-based drugs taken as pills are prescribed to treat the nausea caused by cancer chemotherapy and the loss of appetite that causes “wasting syndrome” in AIDS patients.

    “Snake Oil”

    But 19th-century doctors and druggists also touted cannabis extracts as beneficial for a long list of other problems, ranging from cough, fever, rheumatism, asthma, and diabetes to venereal (sexually transmitted) diseases, like gonorrhea.

    This was still before modern medicine, when lots of herbal products (and even animal products like oil made from rattlesnakes) were sold as “cures” for every disease under the sun. These products were usually ineffective, occasionally harmful, and frequently (as with cannabis and opium extracts) even abused.   

    In 1906, Congress passed the Pure Food and Drug Act, requiring that cannabis and other herbal products be accurately labeled. This was the beginning of laws regulating the sale of cannabis. In later years, some states passed more restrictive laws on cannabis-based medicines as more and more people realized that they could be habit-forming.

    Stay tuned for the final installment of our History of Marijuana series, and find out how cannabis started to be called marijuana.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Clara Mente en su laboratorio

    Algunos de los efectos del THC son útiles en el mundo de la medicina. Por ejemplo, para prevenir la náusea y bloquear el dolor. El truco está en que los científicos logren obtener estos resultados sin los efectos dañinos.

  • Describes trends in high school and youth drug abuse and addiction, with an emphasis on marijuana, cigarettes, prescription drugs, alcohol and ecstasy.

  • The NIDA Blog Team

    As more communities allow medical marijuana, or decriminalize illicit marijuana, veterinarians are seeing an alarming trend. More and more dogs are arriving in emergency animal hospitals with marijuana toxicosis, or marijuana poisoning.

    A recent study in Colorado showed that 4 times as many dogs were treated for marijuana poisoning in 2010 than in 2005. Sadly, two dogs identified in that study died. Similarly, from 2008 to 2013, the Pet Poison Helpline—a poison control hotline for animals—has seen a 200% increase in calls related to pets eating marijuana.

    Most times, dogs ingest marijuana accidentally by eating a marijuana “edibles,” such as cookies or brownies, or getting into their owner’s supply. However, there are some instances where people deliberately give marijuana to their dogs or blow marijuana smoke in their faces to “get them high.” Maybe that sounds funny to people that are high, but it is very dangerous for their dog.


    While it is rare that a dog will die from marijuana poisoning, serious medical issues such as injury or dehydration can occur. Marijuana can cause dogs to become disoriented and lose coordination, leading to missteps and falls, even to the point they can’t drink water from their bowl. Symptoms of marijuana poisoning in dogs include anxiety, panting, lethargy, impaired balance (staggering or being unable to walk), drooling, vomiting, diarrhea, trembling, or extreme responses to noises, movements, or other stimulus.

    So, the next time you see one of those “dogs high on weed” videos on YouTube, give it a thumbs down. And be sure to keep your furry friends away from marijuana. Even if you believe in free choice when it comes to marijuana, you can agree that animals aren’t being given a choice when marijuana is carelessly left out for them to eat or when owners expose them for kicks. Even unintentional exposure from secondhand smoke can be harmful.

    While the debate continues about the usefulness of medical marijuana, some veterinarian groups are looking at using compounds found in the marijuana plant for animals. However, those compounds would be carefully tested and monitored by medical professionals and have no relationship to careless exposure to helpless pets.

    Tell us in comments: What would you do if you knew someone was exposing their dog or other pets to marijuana? 

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Some chemicals in the marijuana plant might be useful in the world of medicine—like preventing nausea and blocking pain, and possibly treating other problems and diseases. The trick is for scientists to get these results without the harmful effects.

    Researchers are studying these chemicals—so that they can develop medications that are chemically similar to THC but don't negatively affect the brain.

  • The NIDA Blog Team

    On this blog, we often get comments from people claiming that marijuana isn’t addictive. A lot of people seem to think marijuana is different from other drugs. Unfortunately, it’s not the case: Just like with other drugs (including alcohol and nicotine), you can get addicted to marijuana—especially if you use it during your teen years.

    Dependence vs. Addiction

    Dependence means needing a drug to feel physically okay. It doesn’t necessarily mean you are addicted—for example, many people can be dependent on a prescribed medication without being addicted. The difference is that people that are addicted start to think about the drug all the time and make it a higher priority than other things in their life; they often make bad decisions that work against their health and their overall well-being. In the case of a medication, they may start to abuse it (using it differently than how the doctor has prescribed) by taking more of it or crushing it and injecting it. Or in the case of a drug like marijuana, they will be unable to stop using it even though it is causing problems with school, jobs, or relationships. People with addictions are often unable to see—or admit—that this is happening.

    One part (but not the only part) of being addicted to a drug is needing the drug to feel physically okay—a condition that is called dependence (see box, “Dependence vs. Addiction”). A person with dependence feels bad when they don’t have the drug, and having enough of a supply is always important to them.

    That Bad Feeling …

    … is called withdrawal. It’s what leads a lot of people who are addicted to a drug to relapse—meaning, they have tried to quit, but start taking the drug again.

    A new study in the Journal of Addiction Medicine shows that teens who use marijuana heavily can experience withdrawal when they stop using it. In a study of teens receiving drug abuse treatment at an outpatient clinic, nearly half of them (40 percent) experienced symptoms of withdrawal when they stopped using marijuana.

    Not Just a Crummy Day

    From portrayals in movies and on TV of people addicted to heroin, people have an image of drug withdrawal as sweating, shaking, and being curled up in bed with unbearable pain. Marijuana withdrawal is a lot more subtle, but every bit as real.

    The main mental symptoms of marijuana withdrawal include:

    • Being irritable
    • Feeling anxious or worried
    • Feeling depressed
    • Being restless
    • Having trouble sleeping at night and feeling tired during the day
    • Having low appetite or losing weight

    Some people having marijuana withdrawal might not realize it. Some of the symptoms just contribute to being in a lousy mood, and it’s often easy to blame that feeling on other people annoying you or just having a bad day. You can also have physical symptoms like:

    • Stomach pain
    • Sweatiness
    • Shakiness
    • Fever
    • Chills
    • Headache

    The longer a person uses marijuana, the more likely they are to have withdrawal symptoms when they aren’t using it. And teen users who suffer marijuana withdrawal are more likely to experience marijuana addiction than adults.  One in six teens who try marijuana will get addicted to it, and that goes up to as many as one-half of teens who use it every day.

    In the Journal of Addiction Medicine study, teens who had marijuana withdrawal symptoms were more likely than other marijuana users to have problems like difficulties at school or at work or trouble with relationships or money. They were also more likely to have other signs of marijuana dependence and mood disorders like depression.

    If you’re worried you may have a problem with marijuana or any other drug, this page may help answer your questions and let you know what to do to get help.

    Tell us in comments: Do you know any regular marijuana users who stop using marijuana and experience the withdrawal symptoms described in this post?

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Sara Bellum

    Knowing the health risks that come with using or abusing drugs convinces most teens (and adults) to stay away from them. But what if you don’t think certain drugs are unsafe?

    In December 2012, NIDA released the results of the 2012 Monitoring the Future (MTF) study (involving 8th, 10th, and 12th graders). The findings show that fewer teens believe abusing marijuana and Adderall is bad for their health. This belief is contributing to higher rates of abuse of these drugs.


    Graph of perceived risk of marijuana use among 12th graders. Over the last 5 years, current (past-month) marijuana use has gone up significantly among 10th and 12th graders. In fact, current marijuana use among high school seniors is at its highest point since the late 1990s. Daily marijuana use has climbed significantly across all three grades. The study also found that fewer teens now believe using marijuana is harmful.

    However, the science shows otherwise. People who smoke a lot of pot risk injuring their lungs with the chemicals found in the smoke, and may also experience depression and anxiety. New research has found smoking marijuana heavily in your teen years and continuing into adulthood can actually lower your IQ!


    Also in the 2012 MTF study, 12th graders reported increased nonmedical use of the prescription stimulant Adderall—commonly prescribed to people with ADHD. As with marijuana, fewer teens perceive that abusing Adderall is risky. If that trend continues, Adderall abuse will probably continue to increase as well.

    Abusing a stimulant medication like Adderall may increase blood pressure, heart rate, and body temperature; decrease appetite and sleep; and cause feelings of hostility and paranoia.

    Perception of Risk

    Studies have found that when teens think a drug can be harmful, they are less likely to abuse it. In the case of marijuana and Adderall, it appears that some teens don’t see the risk. Tell us: Do you think these drugs are dangerous? If you agree they are, what can we do to help people you know get the message?

    Other notable findings from the 2012 MTF study:

    • Most of the top drugs abused by 12th graders are legal substances, like alcohol, tobacco, over-the-counter drugs, and prescription drugs.
    • Abuse of synthetic marijuana—K2 or Spice—remained stable in 2012.
    • Most teens who abuse prescription drugs get them from family and friends.
    • Alcohol use and cigarette smoking are steadily declining.

    Check out this cool infographic to learn more.

    These drug abuse estimates come from the Monitoring the Future study’s national surveys of approximately 45,000 students in about 400 secondary schools each year. View all of the 2012 data.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Presents research-based principles of adolescent substance use disorder treatment; covers treatment for a variety of drugs including, illicit and prescription drugs, alcohol, and tobacco.

  • The NIDA Blog Team

    Not many people would say with a straight face that drugs like heroin or methamphetamine are good for you, let alone they could help you be more successful in life. But there are lots of people who think marijuana is different from other drugs. For example, we’ve already talked in this blog about the idea that it may have medical uses. The jury is still out.

    Some users even say marijuana’s mind-altering effect—the “high”—is also beneficial. They claim using the drug chills them out, expands their mind, and makes them more creative. Since the 1960s, marijuana has had a mystique as an aid to the artistic life.

    What does science say?

    Many studies over the years have found that marijuana indeed makes users perceive themselves as having more creative thoughts and ideas—which would help explain why so many artists and musicians tout its benefits.

    But perception isn’t always the same as reality—and we know that marijuana alters perceptions. In fact, the research on cannabis and creativity suggests that even if users feel more creative, it’s actually an illusion. People may even be less creative after using it.

    For example, a new study of almost 60 cannabis users in The Netherlands looked at the effects of the drug on a measure of creativity called divergent thinking—which means the ability to brainstorm, think flexibly, and come up with original solutions to problems. After inhaling a high or low dose of vaporized cannabis or a vapor with the same odor and taste but no THC (the chemical that causes the high), the participants took a test that asked them to come up with as many creative uses for two common items (like a pen or a shoe) as they could.

    The results surprised even the researchers: Low doses of cannabis did not have any effect on the participants’ ability to think creatively, compared to not taking cannabis. And high doses actually lowered their creativity—by a lot.

    It seems that feeling creative and being creative really aren’t the same thing.

    Yet it is also true that your expectations about a drug do matter. Different studies have shown that people who are unknowingly given a placebo instead of a drug (or alcohol) will act or perform in ways that correspond to how they expect the drug to affect them.

    Marijuana on Your Mind

    One study, for example, found that regular marijuana users who ate biscuits containing marijuana were less creative than a control group who didn’t eat any biscuits, and that both of those groups were less creative than a group who ate biscuits they thought contained marijuana but were actually a placebo.

    It goes to show that your mind, including your beliefs about drugs, have a lot more power than you think. You don’t have to take the drug to get the effect you expect—in fact it works best if you don’t!

    What do you think? Do you know people who take marijuana (or other drugs) to help them be more creative? Do you think it helps or hurts them? Let us know in comments.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • For teachers: Background information and classroom activities for use with the Marijuana Student Booklet.

    Marijuana is the dried leaves and flowers of Cannabis Sativa. Delta-9-tetrahydrocannabinol (THC) is the main active ingredient in marijuana that causes people who use it to experience a calm euphoria. Marijuana changes brain messages that affect sensory perception and coordination. This can cause users to see, hear, and feel stimuli differently and to exhibit slower reflexes.

  • The NIDA Blog Team

    You may know that smoking marijuana can pose risks for a person’s physical health and brain development, especially for teens. But did you know that, for some people, it carries risks for their mental health, too?

    We don’t just mean short-term memory problems or poor judgment—those can happen for anybody who smokes marijuana. We’re talking about serious mental illness.

    Researchers have found that some marijuana users have an increased risk for psychosis, a serious mental disorder where people have false thoughts (delusions) or see or hear things that aren’t there (hallucinations). But there is still a lot to learn about whether marijuana use may lead to this loss of touch with reality, or if having a mental illness makes people more likely to use marijuana. And as with other drugs, things like the age of users, how early they started smoking pot, the amount of the drug they used, and their genetics all could make a difference in whether or not long-term problems develop.

    It’s not your jeans that matter—it’s your genes

    Regular marijuana users with a specific version of a particular gene, AKT1, are at a greater risk of developing psychosis than those who smoke it less often or not at all. How much greater? For people who smoke marijuana daily, the risk is up to seven times greater.

    The reason is that the AKT1 gene affects how much dopamine is released in your brain. Dopamine is one of our brain’s “feel-good” chemicals; it affects important brain functions such as behavior, motivation, and reward. When your brain releases dopamine (for example, after a beautiful bike ride or when you eat a delicious piece of chocolate), the release “teaches” your brain to seek out the same experience (reward) again. Some researchers believe that changes in dopamine levels are linked to psychosis.

    Another study found that adults who used marijuana when they were teenagers and who carried a specific form of another gene for the enzyme COMT (which also impacts dopamine signaling) were at a higher risk of becoming psychotic.

    Are you at risk?

    Right now, unless you’ve had your DNA tested for those specific genes, you don’t know. Many health professionals believe that in the future most of us will know much more about our genetic makeup, but for now and for regular marijuana users, it’s an unknown risk—and you won’t know until you've developed an addiction.

    Even if you don’t have those specific genes, there’s still a risk

    A psychotic event can even happen to pot smokers without these specific genes that put them at risk for long-term serious mental illness. Although rare, marijuana-induced psychosis is becoming more common as people use higher potency forms, including edibles and oil extracts.

    The bottom line? It’s important to know all the risks that can come with using marijuana.

    Brain Science
    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Sara Bellum

    Today, NIDA released the latest results from the 2013 Monitoring the Future (MTF) study, which asks more than 40,000 8th, 10th, and 12th graders about drug, alcohol, and cigarette use. The study revealed both good news and areas for concern.

    First of all, scientists are concerned that only about 40% of 12th graders—that’s 4 out of every 10 teens—believe using marijuana regularly can hurt you. That’s 60% who think marijuana is not harmful! This perception that marijuana use is “okay” is tied to the increases in teens’ use of the drug over the past several years. Science shows that regular marijuana use can be harmful to your health and your future. THC, the main psychoactive ingredient in marijuana, can damage the developing teen brain, yet teens aren’t understanding the connection between marijuana use and the brain’s ability to learn.

    Marijuana use is also putting teens at risk for car accidents—since the drug impairs motor coordination and reaction time. With medical marijuana becoming more accepted and some states making marijuana legal to use, it’s difficult to get these messages to teens.

    There’s other news that worries scientists too: Teens continue to abuse Adderall at a high rate. That drug is usually prescribed for people with ADHD—and when used as prescribed, it can really help. But more than 7% of high school seniors say they use Adderall to get high or for other nonmedical reasons.

    But the survey tells us that teens are getting smarter about a lot of drug use. Cigarette smoking and alcohol use continued to decline in 2013. Also, fewer teens used K2/Spice (sometimes called synthetic marijuana), inhalants, cocaine, and heroin. Fewer teens are abusing prescription painkillers like Vicodin, and very few teens are using bath salts.

    One last note: While cigarette smoking is down, too many teens are still “smoking” by using a hookah (water pipe)—in fact, more than 1 in 5 seniors say they have used a hookah in the past year. Tobacco is no less harmful in a hookah.

    How would you tell other teens that marijuana is, in fact, harmful to their health? How would you change their minds if they think marijuana is harmless? How would you explain to teens that smoking a hookah is just as bad for their health as smoking a cigarette?

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    Using drugs while playing pro sports will usually get a player warned, fined, or suspended. But some people think it’s time to let athletes use marijuana to treat pain from the injuries pro sports can inflict.

    Nate Jackson, who played for the Denver Broncos from 2003 to 2008, says NFL players need marijuana for medical reasons, to help players cope with the frequent injuries—or as he puts it, “to offset the brutality of the game.” In a New York Times opinion piece last year, Jackson argued that marijuana is a better option than handing injured players bottles of prescription opioids, strong pain medications that can be highly addictive. NBA player Blake Griffin has also said that pro athletes might benefit from medical marijuana to treat pain, instead of using prescription painkillers. 

    Is marijuana a good swap for opioids?

    Although prescription opioids are often addictive and can cause confusion and sleepiness, most people who use them as prescribed for acute (severe, often short-term) pain don’t develop an addiction.

    However, a 2009 study commissioned by ESPN (with additional funding from NIDA) found that a lot of NFL players may be misusing opioids during their careers, leading to long-term addiction. Since prescription opioids are chemically similar to heroin, some people who start out abusing prescription opioid pain medications end up using heroin.

    On the other hand, some studies have shown that marijuana (or THC, the active ingredient in marijuana) may help with some types of pain, such as chronic (persistent) nerve pain resulting from injury or surgery. But while the risks associated with marijuana addiction are generally not as severe as the possible risks of prescription opioid addiction, marijuana addiction can develop, as can other health problems. Using weed can impair thinking and memory, for example. Also, THC interferes with parts of the brain that control balance and coordination, which is bad news for athletes who need to be quick on their feet during games.

    THC can also impair concentration and can make people more likely to take risks. (In fact, for some athletes increased risk-taking may be part of marijuana’s appeal. In a 2011 study, researchers (some of them from NIDA) found that some athletes might be using marijuana to forget bad falls, take more risks to improve training, or work through pain.) Not to mention that playing stoned slows people down and makes them less vigilant, which could lead to more athletic injuries. Because of the drug’s health risks, the researchers said they supported banning it from sports.

    So what are players’ options to control injury-related pain?

    For now, athletes can use opioid medications for a short period of time and expect them to help with recovery from injuries. Honest conversations between doctors and their athlete-patients can help lower the risk for addiction—and if problems do develop, those conversations can help people get the professional help they need before they spiral down the black hole of addiction.

    For those athletes (and regular people, too) who have chronic pain, there is research showing that long-term use of opioid medications can actually make pain worse and can lead to addiction. But this is a hotly debated issue, and very smart people disagree with each other. Clearly, more research is needed. At the moment, it’s an individual decision between doctors and their patients on what treatments will work best.

    There are also alternative-medicine approaches for pain that some people have found helpful, such as acupuncture, some nutritional supplements, and chiropractic treatment, among others.

    Where is research (and medicine) heading?

    Marijuana might be of interest to some athletes, but it doesn’t have the NFL’s seal of approval for players looking to treat their pain. And though some states have made it legal for people to use marijuana for medical reasons, it’s important to note that marijuana is still not a medicine approved by the Food and Drug Administration, which approves medicines for the federal government. But NFL Commissioner Roger Goodell says the NFL will “follow medicine” and medical experts in the future, in deciding whether to let players use marijuana to treat head injuries.  

    You may have heard (or read on this blog) about FDA-approved medicines that use some of the chemicals in marijuana, called cannabinoids. These medicines aren’t currently approved in the U.S. for treating pain, though. However, NIDA is funding research into potential use of marijuana and cannabinoids for the treatment of pain—so depending on what the science says, this may change in the future. Stay tuned!

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    Pop Quiz!

    Question: If you look at the candy in the check-out aisle in your local store, an average chocolate bar is 1 serving, and an average bag of candy-covered chocolates (which has about 30 candies) is also 1 serving.

    What is the average serving of a marijuana edible chocolate bar or bag of a candy that has been infused with THC—the active ingredient in marijuana?

    Answer:  There is no average serving.

    Yes, it was a trick question.  But that’s kind of what marijuana edibles are…tricky.  At least for a person who doesn’t use marijuana regularly.

    For example, in Colorado, a single serving of an edible marijuana food product purchased for adult recreational use (as opposed to medicinal use) can’t have more than 10 milligrams of THC in it. BUT, there can be up to ten servings in the product or package. That means a single bag of marijuana candy, a marijuana chocolate bar, a marijuana brownie, or any other marijuana edible might contain as much as 100 milligrams of THC.

    Smoking marijuana delivers to the user about 5 mg of THC in one puff. So if you ate all ten gummies in a bag of marijuana candy—each one a single 10 mg “serving”—it would be like taking 20 hits of a marijuana cigarette at one time!  Because it takes longer to feel the effects of the THC when you eat an edible compared to smoking marijuana—up to an hour or two, this happens a lot.  People end up eating more than the recommended serving because they don’t “feel” it right away.

    But really, it also goes against how most people eat candy.  When was the last time you just had one candy from a bag?

    Beverages containing cannabis can be even more confusing.  For example, one product contains 7.5 servings in a bottle that is about the same size as a can of soda.  Does that mean that you are supposed to take only one sip? A sip and a half? 

    Manufacturers may say it’s a great drink to share, but do you really want to share a bottle with 7.5 friends?  That’s a little too much sharing, if you ask us. (And how do you find half a friend?)

    We all know that these THC-infused edibles and drinks are illegal for teens to use and buy. But many will find ways to try them.  They may find, however, that it isn’t worth long nights coping with overwhelming dizziness, hallucinations, and stomach sickness (common symptoms of overdose)—and for a growing number of unlucky experimenters, trips to the emergency room.

    That’s what happened to New York Times reporter Trish Reske’s 21-year-old son, who had to be rushed to the hospital after eating all 6 servings of a marijuana chocolate bar. Not a great way to spend an evening.

    Tell us in comments: What should manufacturers do to make marijuana edibles safer?

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Mechanism of Action

    woman viewing test tube

    THC, the main active ingredient in marijuana, binds to and activates specific receptors, known as cannabinoid receptors. There are many of these receptors in parts of the brain that control memory, thought, concentration, time and depth perception, and coordinated movement. By activating these receptors, THC interferes with their normal functioning.

  • Describes nationwide trends in drug abuse and addiction, focusing on past-month use for illicit drugs (including marijuana and prescription drugs), alcohol, and tobacco.

  • Sara Bellum

    When you’re driving down the highway at 60 miles per hour, you need a clear head. Driving while distracted by your phone or driving under the influence of alcohol both can lead to crashes and tragedy. Driving under the influence of marijuana is also dangerous, because of the way the drug affects the brain and body.

    Recent news reports have talked about how drugged driving crashes and deaths have surged since medical marijuana has become legal in more states. Now that marijuana is legal for those over age 21 in Colorado and Washington, the rates of drugged driving are likely to increase even more.

    This poses a problem for police and our criminal courts because there isn’t yet a test that can show a person’s marijuana levels the way a “breathalyzer” test can show how much alcohol is in a person’s system in just a few seconds. It also poses a problem for public safety. When people drive after using marijuana, they put themselves, their passengers, and anyone else on the road in danger.

    Evidence from driving studies indicates that marijuana can harm a driver’s ability to pay attention, awareness of time and speed, and ability to draw on information gained from past experiences. Impairment increases a lot when marijuana is combined with alcohol.

    Another problem is that marijuana stays in your system a lot longer than alcohol, which leaves a few hours after you stop drinking. A recent NIDA-funded study looked at long-term marijuana users very closely. The researchers found that even if a person hasn’t used marijuana in a month, it could still be detected in their blood—which may have an effect on a person’s ability to drive safely.

    The bottom line: Use of any mind-altering drug makes it highly unsafe to drive a car and is against the law—just like driving after drinking alcohol.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    Everybody knows how dangerous it is to drink and drive. (A refresher: Drunk driving kills over 10,000 people every year.) That’s why states established a blood alcohol concentration limit for drivers; if you’re pulled over and the alcohol in your breath is above that limit (.08%), you’re considered to be Driving Under the Influence (DUI) or Driving While Impaired (DWI).

    Now, with more states in the U.S. legalizing marijuana for medical and/or recreational use, there’s an increasing need to know the potential risks of “drugged driving.”

    To find out, NIDA joined forces with the Office of National Drug Control Policy (ONDCP), and the National Highway Traffic Safety Administration (NHTSA) for a three-year study on how inhaling marijuana with and without drinking alcohol affects the way people drive. In this two-part series we’ll show you just how they did it, and what they found out!

    Driving without actually driving

    Researchers can now measure driving performance safely, by using the University of Iowa's National Advanced Driving Simulator (NADS), which features state-of-the-art technology to mimic the driving experience in a very convincing way. Other driving simulators are more like video games, but NADS puts you in a real car, surrounded by a 360-degree virtual environment. It also measures tiny details, like where your eyes are looking when you face certain driving obstacles, such as pedestrians and oncoming traffic.

    NADS was developed by NHTSA to enable research that aims to reduce driving accidents, injuries, and deaths by studying how people drive in certain situations, and the ways that certain driving conditions can contribute to safer driving. For instance, what are the safest designs for intersections, entrances and exits, highway signs, and so on?

    It’s a lot less expensive—and yes, a lot safer—to try out different options for roads, signs, etc., without having to actually build them. And a bonus for NIDA’s research: the simulator is just as effective at measuring how people drive under the influence of various drugs.

    Driving Simulator 101: better than Blu-Ray

    The main NADS set-up is a large dome, mounted on a rig that slides and tilts in all directions to give the “driver” sensations of motion. Engineers can install entire cars, and the cabs of trucks and buses, inside the dome. Every vehicle used in the NADS has the exact same interior instruments (dashboard, steering wheel, lighting, etc.) that its real make and model has.

    The motion system creates such a realistic driving experience that drivers feel steering, acceleration, and braking just as they would when driving a real vehicle. The latest visual and audio technology can create all kinds of driving settings and situations: from parking lots to city streets to gravel roads, from oncoming traffic to cars that swerve into your lane as they pass.

    Can you juggle and drive?

    NADS shows a lot more than whether a driver could get into an accident. When you’re driving, it may feel like all you’re doing is watching the road, but you’re actually paying attention to dozens of different things at the same time. It’s kind of like mental juggling.

    For instance, you’re monitoring whether you’re staying in the lane; using peripheral vision to note what’s in your immediate environment; observing what the car in front of you is doing, your distance from it, and what’s behind you in the rearview mirror; keeping tabs on your speed; and a lot more. Hopefully you’re able to keep doing all of that even when momentarily distracted, as when you glance at a GPS.

    NADS is outfitted with interior cameras and other devices that constantly gauge how well a driver handles all these tasks in different driving scenarios. It provides the most thorough data possible on someone’s minute-to-minute driving performance.

    So, back to the NIDA/ONDCP/NHTSA study using NADS: We’ll look at the first set of results in our next post.

    Update: Read Part 2 here!

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    Do you know how long it took for tobacco smoking rates to significantly drop after researchers first linked smoking cigarettes to cancer? 40 years.

    In the 1920s, when the link to cancer was discovered, smoking was normal---in fact, ads for cigarettes even featured doctors saying it relieved stress! For years, people smoked in their homes and offices, in restaurants and stores, on planes and on trains. Wherever they went…they smoked.  In 1957, the nation’s top doctor—the U.S. Surgeon General—warned that cigarette smoking could cause lung cancer. Other government doctors began to speak out.   Still, people continued to smoke.

    Overtime, laws to protect the public’s health limiting where people could smoke, increases in the cost of cigarettes, and the growing body of evidence that smoking was directly linked to lung cancer helped lead turn the tide.   Now, it’s surprising to find people smoking inside—it’s the norm for people to have to go outside.                                                          

    Today, it is marijuana that people, especially younger people, are beginning to view as ‘okay’ or ‘less dangerous’ or ‘normal.’ It reminds us of tobacco nearly 100 years ago—and not in a good way.

    A big difference, though, is for teens —we already know that using marijuana comes with some serious risks. Evidence is strong that smoking marijuana on a regular basis can harm the developing teen brain.  And long-term, regular use of marijuana starting in the teen years can impair brain development and lower IQ.  In other words, the brain may not reach its full potential. 

    As more and more states legalize marijuana for adults, it will likely be easier to get (even for teens), and there’s a chance that the number of people who use it will increase.  For teens, this could have real and lasting effects.  The question is, how long will it take before perception catches up to reality? 

    Scholastics shares the facts surrounding the great marijuana debate with its recent article, ‘Marijuana: Breaking Down the Buzz’.

    Tell us in comments, is marijuana the next tobacco?  Do these facts change your perception?

    For additional facts about the brain and drugs, visit

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Activity One


    The student will understand the effects of marijuana on the brain structures that control the five senses, emotions, memory, and judgment.

    The student will use knowledge of brain-behavior relationships to determine the possible effects of marijuana on the ability to perform certain tasks and occupations.

  • Describes principles important to consider when developing drug abuse prevention programs and discusses issues relevant for family, school, and community settings.

  • Sara Bellum

    Spice, also known as K2 or “synthetic (manmade) marijuana,” is not nice. News stories tell of some really bad effects, like one teen who was paralyzed after using the drug. And the deaths of 3 young people earlier this year in Iowa were also linked to Spice.

    With marijuana use continuing to rise and more states considering making it legal, it is important to get the word out that Spice is not fake marijuana. Calling Spice “fake pot” is just a marketing ploy to attract people to try it, making them believe that it is something familiar.

    In fact, some effects of Spice are much more intense than those of marijuana. Some users experience extreme anxiety, paranoia (believing someone is out to get you), and hallucinations (seeing and hearing things that aren’t real).

    People also report a fast heart rate, vomiting, agitation, and confusion. Spice can also raise blood pressure and cause reduced blood supply to the heart, and in a few cases it has been linked with heart attacks. People who use it a lot may experience withdrawal and addiction symptoms.

    Marijuana does not cause paralysis like in the Texas teen. Spice needs to be treated as a dangerous drug in its own right, not just a manmade form of marijuana.

    The good news is that Spice use is down, especially among high school seniors, who seem to be getting the message that it’s not a drug to mess with. That’s one particularly bright spot in NIDA’s 2013 Monitoring the Future statistics.

    Visit DrugFacts: Spice for more information.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    Our previous post looked at the National Advanced Driving Simulator that NIDA, the Office of National Drug Control Policy (ONDCP), and the National Highway Traffic Safety Administration (NHTSA) used for a three-year study on the effects of marijuana—with and without a low dose of alcohol—on people’s driving. What did the study discover?

    Conducting the study

    First, let’s look at how the study worked. Here are a few of the basics:

    (1) Researchers selected 18 participants between the ages of 21 and 55 who met specific criteria. The participants:

    • reported drinking alcohol and using marijuana no more than three times a week;
    • had been a licensed driver for no less than 2 years, and had a valid unrestricted license; and
    • had driven at least 1,300 miles in the previous year.

    The participants also:

    • had no past or current significant medical illness (i.e., a medical illness with a genuine, noticeable effect on daily life);
    • had no history of a significant negative experience with cannabis or alcohol intoxication, or with motion sickness;
    • were not pregnant or nursing; and
    • were not taking drugs that could cause harm if they were combined with cannabis or alcohol, or that are known to impact driving.

    (2) The participants were given specific amounts of marijuana, alcohol, both, or a placebo (something that wouldn’t get them intoxicated) before each simulated drive. Since the University of Iowa is a non-smoking campus, participants were given vaporized marijuana instead of the kind you smoke.

    (3) After spending the night at the University of Iowa Hospital to ensure that they were sober when the test began, the participants arrived at NADS, consumed the cannabis and/or alcohol or placebo, and then drove in the simulator for 45 minutes. They each did this six times, separated by at least a week between visits.

    One lane per customer

    As we mentioned in the previous post, the National Advanced Driving Simulator (NADS) measures many things about a driver’s behavior—eye movements, reaction times, steering—in lots of driving situations.

    The first results of the study focus on three aspects:

    • how much someone weaved within the lane;
    • the number of times the car left its lane; and
    • how fast the weaving was.

    Remember, the main research question was, What level of ∆9-tetrahydrocannabinol (THC) in the driver’s blood impaired their driving performance similarly to alcohol at the U.S. limit of 0.08%? THC is the main ingredient in marijuana that makes you high.

    The answer: A blood concentration of 13.1 ug/L (micrograms per liter of blood) of THC increased weaving of the car within the lane to the same degree as drivers with a .08% breath alcohol concentration. A single marijuana cigarette can impair your driving skills.

    Not quite “apples to apples”

    It’s important to note that this was the “blood marijuana concentration” recorded during driving, not at the time a person’s blood would be collected after an accident or police stop. Why is that important? Because the concentration of THC in the blood starts to decrease as soon as a person stops using marijuana. By the time a driver gets a blood test, their THC level will be below 13.1 ug/L, but that doesn’t mean they were okay when they were driving.

    Marijuana is often consumed in combination with alcohol. The study found that drivers who used both alcohol and marijuana weaved within lanes, even if their blood THC and alcohol concentrations were below the impairment concentrations of either one when used alone.

    This basically means that when alcohol and marijuana are used together, you need less of each to impair your driving skills. If this sounds complicated, it is. It’s just too risky to drink and drive, or smoke weed and drive.

    Did you miss Part 1? Read it here!

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    In concerts, at house parties, even in the hallway of apartment buildings, you may have come into contact and been exposed to secondhand marijuana smoke.

    In situations like these, people often worry how breathing someone else’s marijuana smoke affects them.  A couple of common questions and the answers may help you see through the fog of this smoky situation.

    Can you get high from inhaling secondhand marijuana smoke?

    Probably not. 

    You may have heard the phrase “contact high,” about someone breathing secondhand marijuana smoke and feeling a buzz.    There have been studies that show in extreme conditions, with lots of smoke blown directly into your face, you can feel the high and it can even show up in a urine test. But this is not a normal circumstance.

    Studies show that very little THC is exhaled back into the air when a smoker exhales. So little, in fact, that if you sat in a room while people exhaled the smoke of four marijuana cigarettes (sometimes called joints) in one hour, you wouldn’t get high.  You would have to be trapped in a room breathing the smoke of 16 burning joints before it you started to show signs of being high. 

    Can you fail a drug test from inhaling secondhand marijuana smoke?

    Again, probably not.

    Since the amount of THC exhaled by marijuana smokers is so low, it would take a lot of secondhand exposure to fail a drug test. 

    In a 2010 study, researchers measured the effect of secondhand marijuana smoke on non-marijuana smokers.  The non-smokers were placed in a well-ventilated space with people casually smoking marijuana for 3 hours.  The researchers then took blood and urine samples from the nonsmokers. They found that THC was present, but the amount was well below the level to needed to fail a drug test.  Another study found similar results: Testing positive is rare and limited to the hours directly following exposure.

    What are the health effects of inhaling secondhand marijuana smoke?

    Researchers are still working to figure this out. We still don’t know how a person is affected if they live with a regular marijuana smoker. We also don’t know how higher amounts of THC in today’s marijuana cigarettes affects secondhand smoke.

    A recent study on rats suggests that secondhand marijuana smoke can do as much damage to your heart and blood vessels as secondhand tobacco smoke. But that study has not yet been done on humans.

    We also know marijuana smoke contains harmful and cancer-causing chemicals, the same way tobacco smoke does. But we still don’t know how it affects a person’s health in the long run. Lots more research still needs to be done. 

    Tell us in comments, what would you do if someone was smoking marijuana near you?

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Activity Two


    The student will understand how marijuana interferes with information transfer and short-term memory.

  • The first in a 5-part series, offers an understanding of the brain, how the reward center works, and what happens in the brain when a person uses cocaine, opiates (heroine), or marijuana.

  • The NIDA Blog Team

    Maybe you’ve heard that marijuana is similar (or identical) to something called hemp. If you’ve seen hemp necklaces or hemp shampoo on store shelves, or heard that Thomas Jefferson, the third president of the United States, grew hemp, you may have wondered: Wait a minute, you mean I can wash my hair with liquid marijuana? Our third president grew weed?

    The answer is more complicated than you might think.

    Here are some facts on hemp and its relation to marijuana:

    What exactly is hemp?

    “Hemp” is another name for the Cannabis sativa plant and its products. This same species of plant is also called marijuana.

    Is hemp the same thing as marijuana?

    Yes and no. Hemp and marijuana are both names for the Cannabis sativa plant, but people usually use these terms to talk about two different varieties of the plant.

    Varieties grown to make hemp rope and other products you see on the shelves (including the varieties Jefferson and others grew during the 1700s) have a whole lot less of the chemical that makes marijuana users feel high. Those varieties are sometimes called “industrial hemp.”

    Varieties grown for use as a drug have been specifically bred to have lots of THC, or delta-9-tetrahydrocannabinol, which is the chemical that makes users feel high.

    What is industrial hemp used for?

    The stalks of industrial hemp—remember, that’s the kind with low levels of THC—can be made into rope, paper, wax, and cloth for furniture or clothes. Sterilized hemp seeds can be made into oil for shampoo, soap, or body lotion. The seeds can also be mixed in with food for animals.

    Is hemp illegal?

    Cannabis sativa is usually illegal under U.S. federal law, but there are exceptions to that rule for products made from hemp that do not contain THC, like paper and shampoo. The U.S. imports some industrial hemp products, and some states also allow farmers to grow industrial hemp.

    What’s the short answer?

    Hemp rope and joints of marijuana come from different varieties of the same plant. The hemp that’s made into rope or jewelry won’t make a person high.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Activity Three


    The student will learn more about the important role of the cerebellum.

  • Provides information about spice, a family of herbal mixtures that produce effects similar to that of marijuana, including how it is used, its popularity among youth, and potential health effects.

  • The NIDA Blog Team

    This is the first post of a 3-part series on the science of medical marijuana.  Check out Part 2: Making Medicine From Marijuana, and Part 3: Medicines or Poisons?—Why Cannabinoids Can Both Help and Hurt You.

    Before modern medical science, most medicines were raw herbs or herbal concoctions of one sort or another. They sometimes helped patients, but those benefits weren’t very powerful by today’s standards, and they often had a lot of unpredictable or even dangerous side effects. That’s because all plants contain hundreds or thousands of different chemicals. If you eat or smoke the leaves of any plant, you are putting all those chemicals in your body, and the results can be unpredictable.

    Marijuana is no different.

    Still, there is growing public support for “medical marijuana,” based on anecdotal evidence (that is, from individual people’s personal experience) that the drug might be useful in treating various diseases, including PTSD (post-traumatic stress disorder), pain, and epilepsy. 

    Voters in 23 states have now passed laws allowing marijuana to be dispensed to patients, as long as they receive permission from a doctor.

    Why Doesn’t the Food and Drug Administration (FDA) Approve “Medical Marijuana”?

    Turns out, there’s very little scientific evidence that smoking or eating marijuana is effective and safe for treating any medical issues. Scientific evidence would have to come from carefully controlled research studies.

    Since there’s no science to back it up, the FDA has not approved smoked or vaporized marijuana for the treatment of any medical condition.

    The FDA only approves medicines when large studies examining lots of patients (called clinical trials) show that the medicines work safely. Without these studies, the FDA can’t promise people that the medications will help them and not harm them. 

    So why haven’t there been clinical trials on marijuana? 

    Because marijuana is a raw herb. There are over 500 different chemicals in marijuana, in combinations that vary widely between different strains and even from plant to plant. This causes serious problems trying to use the whole marijuana leaf, or crude extracts like hash oil, as medicine:

    1. It’s hard to deliver precise, accurate doses of the right chemicals;
    2. It can harm the lungs if users smoke it; and
    3. It causes additional effects—like the “high”—that may interfere with the quality of life of patients taking the drug for serious medical conditions.

    Plus, when used by teens or children, it could even harm their brains as they develop.

    Today, there are almost no approved medicines that are whole herbs. Although it’s not impossible, it would be very unusual if marijuana became an exception.

    So how can we discover and use marijuana’s medical benefits without the harms?

    Stay tuned for Part 2, to learn how scientists are busy trying to create actual medicines from the chemical ingredients in marijuana.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    Smoking marijuana extracts, sometimes called “dabbing,” has become more popular in recent years, and it has some doctors concerned.

    Marijuana extracts—concentrated oils from the marijuana plant (sometimes called “hash oil”)—are a lot stronger than dried marijuana. The higher THC levels are what draw some people to try marijuana extracts. On average, regular marijuana has a THC content of 12–13 percent. (Remember, THC is the chemical in pot that makes users feel high.) But the average marijuana extract has a THC content of more than 50 percent, and some extracts are as much as 80 percent THC!

    Side effects may include explosions

    Because the THC and other chemicals are more concentrated in marijuana extracts than in regular marijuana, the side effects of dabbing—like poor judgment and coordination—are likely to be more powerful than those from smoking weed. Since dabbing is so new, there are not many studies on this yet, unfortunately.

    Marijuana extracts can also be very dangerous to make. One method for extracting the concentrated drug from regular marijuana involves forcing butane (a flammable chemical often found in lighter fluid) through a marijuana-packed pipe. Sometimes it works; sometimes it blows the house up, landing the maker in a burn unit (or worse). 

    Dab at your own risk

    Some scientists have said there should be more public education about the risks of dabbing. In 2014, one study found that, although using dabs didn’t cause more accidents than smoking marijuana buds, the extracts did cause people to build up a higher tolerance to THC and to have more symptoms of withdrawal.

    Also, in a 2015 study, over 80 percent of marijuana extracts studied were contaminated with pesticides or poisonous solvents left over from the extraction process.

    Marijuana in general is bad for teens’ developing brains. A new way to smoke marijuana doesn’t make it any safer.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • You may have heard it called pot, weed, grass, ganja, or skunk, but marijuana by any other name is still a drug that affects the brain.

  • The NIDA Blog Team
    Studies show that marijuana interferes with attention, motivation, memory, and learning. Students who use marijuana regularly tend to get lower grades and are more likely to drop out of high school than those who don’t use. Those who use it regularly may be functioning at a reduced intellectual level most or all of the time.
    Check out NIDA's new infographic that explains what that means in the classroom, and how that can affect your life.  
    [Click here to view larger version of this infographic or the text-only version]
    Marijuana Use & Educational Outcomes Infographic
    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Es posible que la hayas oído llamar "yerba", "mota", "mafu", "pasto", "maría" y "café" en español, o "pot", "weed", "grass", "ganja" y "skunk" en inglés. Sin embargo, no importa cómo la llames, la marihuana sigue siendo una droga que afecta al cerebro.

  • Explores the latest research on marijuana, including the scope of marijuana use in the U.S., health consequences, its effects on everyday activities, and available treatments.

  • The NIDA Blog Team

    This is the second post of a 3-part series on the science of medical marijuana.  Check out Part 1: What’s Wrong With “Medical Marijuana”? and Part 3: Medicines or Poisons?—Why Cannabinoids Can Both Help and Hurt You.

    What people usually mean by “medical marijuana” is use of an unprocessed (raw) plant to treat illness—or herbal medicine, in other words. Unprocessed means the leaves, stems, or seeds are just taken off the plant and used.

    Before the 20th century, that’s mostly what medicine was.

    But science has made a lot of progress in the last several decades, and generally it hasn’t looked back. It’s because we now have ways of picking out the specific chemicals that are useful from plants and putting just those parts in a pill, without all the unwanted chemicals that might cause side effects or even be toxic.

    This is what a lot of scientists are busy doing right now with marijuana—trying to figure out which chemicals in the plant really are useful in treating health problems and then finding ways to deliver them safely and effectively to patients to treat their conditions.

    Turning Marijuana into Medicine

    At the last count, scientists have found over 500 separate chemicals in the marijuana plant. The main chemical that gives users the “high” is tetrahydrocannabinol, or THC, but there are over 100 other chemicals in marijuana that have a similar molecular structure to THC. This family of chemical compounds is called cannabinoids.

    So far, there are two FDA-approved medications containing THC for treating nausea and appetite problems caused by cancer chemotherapy and AIDS. Other drugs with THC in them have been approved already in other countries for treating symptoms of multiple sclerosis (MS) and are now being carefully tested before being approved in the United States.

    Another marijuana chemical is cannabidiol, or CBD. News reports have highlighted some families who are living in states where medical marijuana is legal so their children with bad forms of epilepsy can get special high-CBD marijuana extracts to help control seizures.

    These extracts probably still contain other, possibly harmful ingredients. But a medicine only containing CBD is now being tested in the United States. If the science finds that CBD really is a good treatment for seizures, eventually patients may be able to take that or another safe, CBD-based medication. This could help people get the safe treatment they need.

    Cannabinoids and Other Diseases

    Lots of different cannabinoid chemicals are being studied to see whether they have beneficial effects on conditions ranging from addictions and other mental health problems to pain and other serious conditions. Most are still a long way from being studied in humans and going on to become medications.

    In Part 3, we’ll look at why chemicals in the marijuana plant could be so helpful even though they may also be harmful. It turns out, marijuana’s not unique in being two-faced!

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • The NIDA Blog Team

    The Super Bowl is only a few days away. From the game itself to the halftime show to the commercials (of course!), the event has something for everyone. Most people who tune in, however, won’t realize that behind the scenes, a different competition is going on: the National Football League (NFL) vs. drug use.

    Some NFL players may abuse prescription drugs to cover up the pain that can result from football-related injuries. Or they may take performance-enhancing drugs (PEDs), like anabolic steroids, trying to make themselves stronger and (they hope) play a better game.

    The NFL’s drug policy—which it developed along with the NFL Players’ Association (NFLPA)—takes a stand against PEDs as well as other substances. But the policy doesn’t score with some critics, who think it isn’t strict enough.

    No illegal kicks

    The League bans players from using, possessing, or distributing drugs like cocaine, marijuana, painkillers such as opioids, MDMA (Molly or Ecstasy), and PCP. Amphetamines are also banned unless the player has a genuine, proven need to use them for a medical condition. The policy also covers alcohol use that’s associated with breaking the law: for instance, failing an alcohol breath test.

    In 2014, the NFL and NFLPA agreed on a separate policy for PEDs. It bans players’ use of anabolic steroids, stimulants, human or animal growth hormones, and related PEDs.

    NFL players are tested for drugs at certain points throughout the season, and again at other times if a player fails a drug test, or is arrested in connection with drug use, or shows signs of drug abuse.

    Time to move the goalposts?

    If a player violates the NFL’s drug policy once, he receives 90 days of treatment and the unannounced testing. Second-time violators get two years of treatment and testing, plus a four-game suspension if they don’t stick with the treatment or they test positive. Three-time offenders who don’t stay with treatment or who have a positive test for marijuana get a 10-game suspension, and a year-long ban from the League for using other drugs.

    People who think the NFL drug policy should be tougher point to players like Josh Gordon, the Cleveland Browns’ 24-year-old wide receiver, who has already faced four suspensions (two of them lasting a year each). And in 2014, there were 41 drug-related suspensions in the League—an all-time record—and the current season may break that record.

    A lot of people look up to the players, and critics worry that when so many NFL players are violating drug policy, it sends a bad message. The League may or may not “move the goalposts” for players who use drugs—but either way, the consequences for those players are a reminder that using banned or illegal drugs for any reason is a losing game.

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Hi, my name is Sara Bellum. Welcome to my magazine series exploring the brain's response to drugs. In this issue, we'll investigate the fascinating facts about marijuana.

    You may have heard it called pot, weed, grass, ganja or skunk, but marijuana by any other name is still a drug that affects the brain.

  • The NIDA Blog Team

    Note: This post has been updated since the original posting date.

    Last week, the American Academy of Pediatrics (AAP), an organization that represents doctors who specialize in treating children and adolescents, published a statement opposing most uses of medical marijuana and the legalization of marijuana, because of the possible ways the drug can harm young people.

    You’re aware that there’s been a lot of talk about whether the government should relax its marijuana laws, or even make it legal. There are lots of strong opinions for and against. So far, voters in four states and the District of Columbia have voted to legalize adult recreational use of marijuana.

    Nearly half of the states have also passed laws allowing medical use of marijuana, even though so far there’s very little science supporting it. The Food and Drug Administration (FDA), which puts its stamp of approval on medicines, has never approved it.

    Doctors who treat young people are worried about the long-term dangers of exposure to marijuana when the brain is still growing—usually until you’re in your early 20s. Studies show that young people are especially vulnerable to becoming addicted to drugs, including marijuana. And heavy use of marijuana in the teen years has been linked with loss of IQ—which can potentially have a domino effect in a person’s life: worse grades, worse jobs, worse relationships, and so on.…

    The AAP also recommended that, in places where marijuana has already been legalized, authorities take steps to keep it out of the hands of young people and to place limits on advertising that might make it seem appealing to kids.

    Although the AAP is opposed to most medical marijuana—and especially against using marijuana to treat children and teens—it does support loosening the legal restrictions (“scheduling”) on marijuana that sometimes make it hard for researchers to study the possible health benefits of the plant and the cannabinoid chemicals it contains. More research could lead to FDA-approved drugs that use these potentially healing chemicals, but do not require smoking the plant, which can affect your lung health.

    Tell us what you think: Are these doctors right? Do you think more kids would use marijuana if it was made legal? Do you think most teens realize their brain is still growing and could be affected by marijuana use?  

    Comments posted to the Drugs & Health Blog are from the general public and may contain inaccurate information. They do not represent the views of NIDA or any other federal government entity.
  • Clara Mente estudiando una hoja de marihuana

    Me llamo Clara Mente y quiero darles la bienvenida a mi serie de boletines informativos que exploran la respuesta del cerebro a las drogas. En este ejemplar, investigaremos varios datos fascinantes sobre la marihuana. Alguna de esta información fue descubierta recientemente por los científicos que lideran la investigación en este campo.

  • Presented in question-and-answer format and targeted to teens, provides facts about marijuana and its potential harmful effects.

  • What Is Marijuana?

     A hand holding a Marijuana leaf

    Also known as: “weed,” “pot,” “bud,” “grass,” “herb,” “Mary Jane,” “MJ,” “reefer,” “skunk,” “boom,” “gangster,” “kif,” “chronic,” and “ganja”

    Marijuana is a mixture of the dried and shredded leaves, stems, seeds, and flowers of Cannabis sativa—the hemp plant. The mixture can be green, brown, or gray. Stronger forms of the drug include sinsemilla (sin-seh-me-yah), hashish (“hash” for short), and hash oil.

    Of the more than 500 chemicals in marijuana, delta-9-tetrahydrocannabinol, known as THC, is responsible for many of the drug’s psychotropic (mind-altering) effects. It’s this chemical that changes how the brain works, distorting how the mind perceives the world.

    Legal Issues

    It is illegal to buy, sell, or carry marijuana under Federal law. The Federal Government considers marijuana a Schedule I substance—having no medicinal uses and high risk for abuse. However, across the United States, marijuana state laws for adult use are changing. A growing number of states have passed laws allowing the use of marijuana as a treatment for certain medical conditions.

    In addition, four states and the District of Columbia have legalized marijuana for adult recreational use. Because of concerns over the possible harm to the developing teen brain and the risk of driving under the influence, marijuana use by people under age 21 is prohibited in all states.

    Strength and Potency

    The amount of THC in marijuana has increased over the past few decades. In the early 1990’s, the average THC content was about 3.74 percent for marijuana and 7.5 percent for sinsemilla.In 2013, it was almost 10 percent for marijuana and 16 percent for sinsemilla in 2013.1 Scientists don’t yet know what this increase in potency means for a person’s health. It could be that users take in higher amounts of THC, or they may adjust how they consume marijuana (like smoke or eat less) to compensate for the greater potency.

    Hash Oil

    The honey-like resin from the marijuana plant has 3 to 5 times more THC than the plant itself. Smoking it (also called “dabbing”) can deliver dangerous amounts of THC to users, and has led some people to the emergency room. People have been burned in fires and explosions caused by attempts to remove hash oil using butane (lighter fluid).

    1. ElSohly MA. Potency Monitoring Program quarterly report number 124. Reporting period: 12/16/2013 -03/15/2014. Bethesda, MD: National Institute on Drug Abuse; 2014.


  • How Is Marijuana Used?

    Marijuana is commonly smoked using pipes, water pipes called “bongs,” or hand-rolled cigarettes called “joints” or “nails.” It is sometimes also combined with tobacco in partially hollowed-out cigars, known as “blunts.” Recently vaporizers, that use heat without burning to produce a vapor, have increased in popularity. Marijuana can also be brewed as tea or mixed with food, sometimes called edibles.

    In addition, concentrated resins containing high doses of marijuana’s active ingredients, including honey-like “hash oil,” waxy “budder,” and hard amber-like “shatter,” are increasingly popular among both recreational and medical users.

  • How Does Marijuana Affect the Brain?

    The main chemical in marijuana that affects the brain is delta-9-tetrahydrocannabinol (THC). When marijuana is smoked, THC quickly passes from the lungs into the bloodstream, which carries it to organs throughout the body, including the brain. As it enters the brain, THC attaches to cells, or neurons, with specific kinds of receptors called cannabinoid receptors. Normally, these receptors are activated by chemicals that occur naturally in the body. They are part of a communication network in the brain called the endocannabinoid system. This system is important in normal brain development and function.

    Most of the cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thinking, concentration, sensory and time perception, and coordinated movement. Marijuana triggers an increase in the activity of the endocannabinoid system, which causes the release of dopamine in the brain's reward centers, creating the pleasurable feelings or “high.” Other effects include changes in perceptions and mood, lack of coordination, difficulty with thinking and problem solving, and disrupted learning and memory.

    Certain parts of the brain have a lot of cannabinoid receptors. These areas are the hippocampus, the cerebellum, the basal ganglia, and the cerebral cortex. (Learn more about these areas and how THC affects them.) The functions that these brain areas control are the ones most affected by marijuana:

    Marijuana's Effects on the Brain
    • Learning and memory. The hippocampus plays a critical role in certain types of learning. Disrupting its normal functioning can lead to problems studying, learning new things, and recalling recent events. A recent study followed people from age 13 to 38 and found that those who used marijuana a lot in their teens had up to an 8 point drop in IQ, even if they quit in adulthood.3,4
    • Coordination. THC affects the cerebellum, the area of our brain that controls balance and coordination, and the basal ganglia, another part of the brain that helps control movement. These effects can influence performance in such activities as sports, driving, and video games.
    • Judgment. Since THC affects areas of the frontal cortex involved in decision making, using it can cause you to do things you might not do when you are not under the influence of drugs—such as engaging in risky sexual behavior, which can lead to sexually transmitted diseases (STDs) like HIV, the virus that causes AIDS—or getting in a car with someone who’s been drinking or is high on marijuana.

    When marijuana is smoked, its effects begin almost immediately and can last from 1 to 3 hours. Decision making, concentration, and memory can suffer for days after use, especially in regular users.2

    If marijuana is consumed in foods or beverages, the effects of THC appear later—usually in 30 minutes to 1 hour—but may last for many hours.

    Long-term, regular use of marijuana—starting in the teen years—may impair brain development and lower IQ, meaning the brain may not reach its full potential.3,4

    Learn more about how the brain works and what happens when a person uses drugs.

    2. Crean RD, Crane NA, Mason BJ. An evidence based review of acute and long-term effects of cannabis use on executive cognitive functions. Journal of Addiction Medicine 2011;5:1-8.

    3. Zalesky A, Solowij N, Yücel M, et al. Effect of long-term cannabis use on axonal fibre connectivity. Brain 2012;135:2245-55.

    4. Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings of the National Academy of Sciences U S A 2012;109:E2657-64.


  • What Are the Other Effects of Marijuana?

    The changes that take place in the brain when a person uses marijuana can cause serious health problems and affect a person’s daily life.

    Effects on Health

    Within a few minutes after inhaling marijuana smoke, a person’s heart rate speeds up, the bronchial passages (the pipes that let air in and out of your lungs) relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. While these and other effects seem harmless, they can take a toll on the body.

    • Increased heart rate. When someone uses marijuana, heart rate—normally 70 to 80 beats per minute—may increase by 20 to 50 beats per minute or, in some cases, even double. This effect can be greater if other drugs are taken with marijuana. The increased heart rate forces the heart to work extra hard to keep up.
    • Respiratory (lung and breathing) problems. Smoke from marijuana irritates the lungs, causing breathing and lung problems among regular users similar to those experienced by people who smoke tobacco—like a daily cough and a greater risk for lung infections such as pneumonia. While research has not found a strong association between marijuana and lung cancer, many people who smoke marijuana also smoke cigarettes, which do cause cancer. And, some studies have suggested that smoking marijuana could make it harder to quit cigarette smoking.5
    • Increased risk for mental health problems. Marijuana use has been linked with depression and anxiety, as well as suicidal thoughts among adolescents. In addition, research has suggested that in people with a genetic risk for developing schizophrenia, smoking marijuana during adolescence may increase the risk for developing psychosis and developing it at an earlier age. Researchers are still learning exactly what the relationship is between these mental health problems and marijuana use.
    • Increased risk of problems for an unborn baby. Pregnant women who use marijuana may risk changing the developing brain of the unborn baby. These changes could contribute to problems with attention, memory, and problem solving.

    Effects on School and Social Life

    The effects of marijuana on the brain and body can have a serious impact on a person’s life.

    • Reduced school performance. Students who smoke marijuana tend to get lower grades and are more likely to drop out of high school than their peers who do not use. The effects of marijuana on attention, memory, and learning can last for days or weeks. These effects have a negative impact on learning and motivation. In fact, people who use marijuana regularly for a long time are less satisfied with their lives and have more problems with friends and family compared to people who do not use marijuana.
    • Impaired driving. It is unsafe to drive while under the influence of marijuana. Marijuana affects a number of skills required for safe driving—alertness, concentration, coordination, and reaction time—so it’s not safe to drive high or to ride with someone who’s been smoking. Marijuana makes it hard to judge distances and react to signals and sounds on the road. Marijuana is the most common illegal drug involved in auto fatalities. High school seniors who smoke marijuana are 2 times more likely to receive a traffic ticket and 65% more likely to get into an accident than those who don’t smoke.6 In 2011, among 12th graders, 12.5% reported that within the past 2 weeks they had driven after using marijuana.7 And combining marijuana with drinking even a small amount of alcohol greatly increases driving danger, more than either drug alone. Learn more about what happens when you mix marijuana and driving.
    • Potential gateway to other drugs. Most young people who use marijuana do not go on to use other drugs. However, those who use marijuana, alcohol, or tobacco during their teen years are more likely to use other illegal drugs. It isn’t clear why some people do go on to try other drugs, but researchers have a few theories. The human brain continues to develop into the early 20s. Exposure to addictive substances, including marijuana, may cause changes to the developing brain that make other drugs more appealing. Animal research supports this possibility—for example, early exposure to marijuana makes opioid drugs (like Vicodin or heroin) more pleasurable. In addition, someone who uses marijuana is more likely to be in contact with people who use and sell other drugs, increasing the risk for being encouraged or tempted to try them. Finally, people at high risk for using drugs may use marijuana first because it is easy to get (like cigarettes and alcohol).

    For more information on the effects of marijuana, see our Marijuana Research Report.

    5. Panlilio, LV, et al. Prior exposure to THC increases the addictive effects of nicotine in rats. Neuropsychopharmacology (2013) 38, 1198–1208.

    6. U.S. Department of Transportation. National Highway Traffic Safety Administration. Traffic Safety Facts. Drug Involvement of Fatally Injured Drivers. Washington, DC, November 2010. Available at:

    7. O’Malley, P.M.; Johnston, L.D. Driving after drug or alcohol use by U.S. high school seniors, 2001–2011. American Journal of Public Health 103(11):2027-2034, 2013.


  • Can You Get Addicted to Marijuana?

    Yes, marijuana is addictive. A user may feel the urge to smoke marijuana again and again to re-create the “high.” Repeated use could lead to addiction—which means the person has trouble controlling their drug use and often cannot stop even though they want to.

    An estimated nine percent of people who use marijuana will become dependent1,2; people who begin using marijuana before the age of 18 are 4-7 times more likely to become addicted than adults.3

    It is estimated that about 1 in 6 people who start using as a teen, and 25% to 50% percent of those who use it every day, become addicted to marijuana. What causes one person to become addicted to marijuana and another not to depends on many factors—including their family history (genetics), the age they start using, whether they also use other drugs, their family and friend relationships, and whether they take part in positive activities like school or sports (environment).

    People who use marijuana may also feel withdrawal when they stop using the drug. Withdrawal symptoms may include:

    • Irritability
    • Sleeplessness
    • Lack of appetite, which can lead to weight loss
    • Anxiety
    • Drug cravings

    These effects can last for several days to a few weeks after drug use is stopped. Relapse (returning to the drug after you’ve quit) is common during this period because people also crave the drug to relieve these symptoms.


    1Anthony, J., Warner, L.A., Kessler, R.C. Comparative epidemiology of dependence on tobacco, alcohol, controlled substances, and inhalants: basic findings from the National Comorbidity Survey. Experiments in Clinical Psychopharmacology. 1994; 2:244-268.

    2Lopez-Quintero, C., Perez de los Cobox, J., Hasin, D.S., et al. Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: results of the Natioanl Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug and Alcohol Dependence. 2011; 115(1-2): 120-130.

    3Winters, K. C. & Lee, C.Y. S. Likelihood of developing an alcohol and cannabis use disorder during youth: Association with recent use and age. Drug and Alcohol Dependence. 2008; 92, 239–247.


  • Can You Die If You Use Marijuana?

    It is very unlikely for a person to overdose and die from marijuana use. However, people can and do injure themselves and die because of marijuana's effects on judgment, perception, and coordination, for example, when driving under the influence of the drug. Also, people can experience extreme anxiety (panic attacks) or psychotic reactions (where they lose touch with reality and may become paranoid).

  • How Many Teens Use Marijuana?

    Marijuana is the most common illicit drug used in the United States by teens as well as adults. The growing belief by young people that marijuana is a safe drug may be the result of recent public discussions about medical marijuana and the public debate over the drug’s legal status. In addition, some teens believe marijuana cannot be harmful because it is “natural.” But not all natural plants are good for you—take tobacco, for example.

    See the most recent statistics on teen drug use from NIDA’s Monitoring the Future study below:

    Swipe left or right to scroll.

    Monitoring the Future Study: Trends in Prevalence of Marijuana/ Hashish for 8th Graders, 10th Graders, and 12th Graders; 2015 (in percent)*
    Drug Time Period 8th Graders 10th Graders 12th Graders
    Marijuana/ Hashish Lifetime 15.50 [31.10] 44.70
    Past Year 11.80 25.40 34.90
    Past Month 6.50 14.80 21.30
    Daily 1.10 3.00 6.00

    For more statistics on teen drug use, see NIDA’s Monitoring the Future study.

  • What Is Medical Marijuana?

    The marijuana plant contains chemicals that may be useful for treating a range of illnesses or symptoms. A growing number of states have legalized the plant’s use for certain medical conditions. Read more about marijuana-related state laws.

    Although it is not legal or considered medicine by the Federal Government a few medications made from active chemicals in the plant called cannabinoids have been approved by the U.S. Food and Drug Administration (FDA). One of these cannabinoids, THC, has some medicinal properties in addition to its mind-altering effects. Pill versions of THC have been approved to treat nausea (feeling sick) in cancer patients and to increase appetite in some patients with AIDS.

    Another cannabinoid chemical called cannabidiol, which doesn’t have mind-altering effects, is also being studied for its possible uses as medicine. A new medication with a combination of THC and cannabidiol is available in several countries outside the United States as a mouth spray for treating symptoms of multiple sclerosis. There is some early evidence that cannabidiol may be useful in treating seizures in children with severe epilepsy, so a cannabidiol-based drug for that is also now being studied.

    It is important to remember that because marijuana is often smoked, it can hurt lung health; these health risks as well as the way it impairs mental functioning may outweigh its value as a medical treatment, especially for people that are not very sick with cancer or other life-threatening diseases. Another problem with smoking or eating marijuana plant material is the ingredients vary a lot from plant to plant, so there is no way to get a precise dose every time or even know what dose you are getting. This is why scientists are busy studying safe ways that THC, cannabidiol, and other chemicals can be extracted from the marijuana plant to create safe medicines. 

    For more information, see Drug Facts—Is Marijuana Medicine?

  • What Should I Do If Someone I Know Needs Help?

    If you or a friend are in crisis and need to speak with someone now, please call:

    • National Suicide Prevention Lifeline at 1-800-273-TALK (they don't just talk about suicide—they cover a lot of issues and will help put you in touch with someone close by).

    If you need information on treatment and where you can find it, you can call:

    For more information on how to help a friend or loved one, visit our Have a Drug Problem, Need Help? page.

  • For More Information on Marijuana