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Drugs & Health Blog

Can It Be Bad If It’s Natural?

This blog post is archived and is no longer being updated. For the latest content, please visit the main Drugs & Health Blog page.
Eric Wargo, NIDA Science Writer

“Marijuana is natural, so how can it be harmful?”

Lots of teens ask us this question, and it’s a good one.

People often think that substances found in nature are automatically safer than chemicals that are made in a laboratory or a factory. It’s not that simple, unfortunately. Lots of beneficial substances are human made (medicines, for example), and lots of harmful ones come straight from the earth.

A brief history of tobacco

Tobacco is a great example. Like marijuana, tobacco is a plant whose leaves have been dried, crumbled, and smoked for thousands of years. It was used in religious rituals by Native Americans, who believed that exhaling tobacco smoke carried their thoughts and prayers to heaven; they also believed it possessed medicinal properties.

Once American settlers began growing the crop and exporting it to Europe and the rest of the world, tobacco enjoyed a reputation kind of like marijuana does today: Some monarchs and religious leaders thought it was unhealthy and morally corrupt and tried to ban it; but lots of people enjoyed the “precious weed” and sided with the physicians of the time, who actually praised its healing virtues—claiming that smoking tobacco could cure most forms of sickness and even protect a person from getting the plague!

It wasn’t until around the 1950s that modern medicine, armed with better science, established the truth about smoking tobacco—it can cause diseases like lung cancer and it is highly addictive. No one would now argue that tobacco is safe, let alone good for you. But it is “natural.”

Natural does not equal safe

Marketers of foods and other products use the “natural equals good for you” assumption all the time to manipulate people’s buying behavior. For instance, when shoppers see the “All Natural” label on a food, they tend to think it’s good for them even if it contains lots of unhealthy sugar or fat—both of which are, like tobacco, “natural.”

We still don’t know whether smoking marijuana causes lung cancer like tobacco does, but strong evidence shows that it does other bad stuff: It interferes with thinking and memory, it can lower your IQ if you smoke it regularly in your teen years, and—as a result of these and other things—it can set you up to miss achieving your full potential in life.

Is a “natural” way to hurt your brain any better than an unnatural one?

Eric Wargo is a science writer at NIDA. Before coming to NIDA, he wrote for an association of psychological scientists, people who study all aspects of the mind and human behavior. He is excited to work at NIDA, because NIDA scientists study the brain, and the brain is at the root of everything we humans do.

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.


Even though marijuana is a natural resource, it is important to know the consequences of consuming it. Because of its highly dangerous effects on our brain and many of our vital organs, it is important to be educated about its risks and be aware of the harm it can do to our bodies. I hope that in the future, we will have many more people educated about marijuana, to prevent people from making a life-threatening decision.
I agree that marijuana is bad for your health. I can see it's usefulness for medicinal purposes, but if it was legalized it would be too easy for it to be abused. There is plenty of medication in the world today to help with many medical issues, so why do people want to legalize something they know is harmful to them? There are always people who want to use things for their own personal gain, and legalized marijuana would just be another thing to add to their lists. Drug abuse is one thing, another would be the tyranny brought by companies looking to sell the addictive substance to addicted users; just like tobacco. Why not just leave sleeping dogs lay and keep marijuana banned?
just because a plant is natural, doesnt mean its good for you. Tobacco and marijuana do not heal, or make anything better. It's like saying that tobacco is a cure for everything yet it gives you cancer.. Marijuana may cure you, but on the other hand, it also affects you in some way just like tobacco does.
Can it be bad for you if its natural? This is quite a strong statement/question, which made me think twice about the subject. So can it be bad if its natural? After reading this article I believe so, it is quite a serious subject to discuss and I think it is great that we are being exposed to these areas of learning at such a young age, this information can be most beneficial for us from this age forward. Marijuana is a terrible drug which should be taken more seriously, it can cause all sorts of consequences such as long term damage to the brain and lower your iQ levels. it is also most definitely not ALL natural, marijuana is a plant that causes a chemical reaction to the body giving the person which inhaled it a "high", and although its grown in the ground, it is often sprayed with pesticides to prevent bugs from getting to it. After that, in some cases people use their bath tub to add extra chemicals such as bleach and rat poison! Not to mention all the other harmful substances added. After knowing this, do you still want to smoke it, to be inhaling all of these things and more? I sure wouldn't be. Marijuana is a very misleading drug and many mistake it for being better for you because it's grown naturally, but clearly it is just as harmful as every other drug, and should not be taken lightly.
i agree that marijuana is very bad for you and it should be illegal. it is a drug that causes brain damage and you have to be a pretty stupid person to take it. even if its natural, its a natural POISON !
I agree that marijuana is a very bad substance so therefore it should be illegal all around the world. Don't be fooled because when something is natural, it doesn't always necessarily mean it's good for you, in fact a lot of the times is bad for your health. Is it really worth putting your body at risk with all the dangers such as lowering your IQ, making it difficult for you to recall recent events and contains the dangerous chemical called THC (Tetrahydrocannabinol).
If it is natural then it can't be that bad because people use it to relieve the pain off a cancer patient,and it also kills cancer cells

@Zach R Even if marijuana makes a person feel better, it doesn’t mean it is good for them. Not only are they treating their pain symptoms at the expense of their mental functioning, they are exposing themselves to long-term health risks, including addiction. If they are an adolescent, they could permanently be lowering their IQ. Contrary to what many people say, marijuana is not medicine. Getting insurance and real medical treatment for their condition is the best alternative.

For more information about marijuana for medical use visit:

Where is your information backed up by serious scientific studies conducted across a broad variety of peoples? You are a government pawn and the sooner you realize it the happier you will be. Marijuana can CURE cancer. Yet you downplay the healing abilities of it. Since the 1920's the reefer madness campaign has repeated the exact same rhetoric you are spewing into the world, I have an IQ of 150, I have been an avid marijuana user since my prepubescent years, your entire article is based upon Nancy and Ronald Reagans failed war on drugs. You are an embarrassment to the American people you serve. To think you waste our tax dollars trying to slander and smear the uses of one of the most revolutionary plants in existence. NIDAMINDS you make me sick.

For information on marijuana research and references to specific scientific studies, see

it cant cure cancer it can stop people from hurting themselves in a sezure though
In my opinion marijuana is a very un natural, and a bad thing to get attached and addicted too. Although you cant help it, it is not something you can control. Although it can be treated.
you guys are so ignorant. you all say that weed is bad for you but yet it has its medical uses. unlike alchohol and tabacco they cause cancer and sclerosis in the liver. have you seen weed do that to somene? no, but i bet you guys can see marijuanna help prevent glaucoma and relieve pain for cancer victims. i beleive marijuanna should be legal all over the worl medically but not for reacreation...
Opiates are all natural, so is peyote, cyanide, and mercury. Natural does not = safe.
Why is marijuana illegal and tobacco and alcohol, which are more addictive and can kill, are legal? Is it because of racism? My friend told me there was this guy Harry Anslinger who played on white racial fears to make marijuana illegal even though doctors said it was not dangerous or addictive.

That's a good question, Chogyam Trungpa.  Marijuana was made illegal because it was thought to have a high potential for abuse, it was unsafe, and it had no medical use.  That was many years ago.  Science has shown us that marijuana can benefit those with chronic pain and other illnesses. Many states and local communities are decriminalizing it's use and even legalizing it for medicinal use. 

Those that make the natural gotta be good argument have not taken the time to research or understand their argument, it just sounds good to them. Many plants are poisonous and some are deadly. If the natural gotta be good argument is true. Other drugs would fit into this category. Heroin/opium, cocaine, and meth all occur naturally in plants and all have medical uses.
this is so dumb. "IF ITS SO BAD WHY DO PEOPLE DO IT?"
Why do people do Marijuana?
It's amazing to me that the so called experts don't tell people that you can't overdose and DIE from marijuana. Although all prescription medicine can kill you by an overdose, even aspirin which is a non-prescription drug. I feel it's time to help people.
smoke weed everyday
If we make pot illegal might as well make liquor and cigarettes illegal... They are all the same.. In MY OPINION I think it should be legal...
The thing that makes the tobacco addictive is nicotine. Tobacco (by its self) is as harmless as marijuana, being as it causes damage to the lungs.
would you eat deadly nightshade because it is natural no it could kill you and/or put you in a coma
If it's so harmful, why is there no evidence? Willie Nelson is 84 & is still performing, he has smoked the herb all his life, shouldn't we be seeing evidence of harm in him by now?

This is a very interesting question. We don’t know anything about how much marijuana Willie Nelson smokes, or about his recent respiratory medical condition that was reported in the news---he even apologized on his website, because he had to cut short part of his tour. But there is clear evidence that smoking anything is not good for your lungs. And it is all about how much risk you are willing to take. For example, there are many people who smoke cigarettes all their lives and don’t get lung cancer. But if you do smoke, you are much more likely to get it. Like tobacco smoke, marijuana smoke is an irritant to the throat and lungs and can cause a heavy cough during use. It also contains levels of volatile chemicals and tar that are similar to tobacco smoke, raising concerns about risk for cancer and lung disease One study found that people who frequently smoke marijuana had more outpatient medical visits for respiratory problems than those who do not smoke. Here are the names of two studies you can find online: 1. Tashkin DP. Effects of marijuana smoking on the lung. Ann Am Thorac Soc. 2013;10(3):239-247. doi:10.1513/AnnalsATS.201212-127FR. 2. Owen KP, Sutter ME, Albertson TE. Marijuana: respiratory tract effects. Clin Rev Allergy Immunol. 2014;46(1):65-81. doi:10.1007/s12016-013-8374-y.


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