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How Do Prescription Drugs Affect the Body, and What Are the Common Effects?

Abusing prescription drugs can have negative short- and long-term health consequences. Opioids, central nervous system depressants, and stimulants each affect the brain and body in different ways.

• Opioids attach to specific proteins called opioid receptors, which are found in the brain, spinal cord, gastrointestinal tract, and other organs. When opioid drugs attach to these receptors, they can diminish the perception of pain. They also affect areas of the brain that deal with pleasure—which is why they are often abused and why they can be addictive.

  Opioids also cause drowsiness, constipation, and physical dependence with repeated use (or abuse). An overdose of opioids can cause breathing to slow down so much as to cause death. Overdose can occur when people take too high a dose; when they crush a time-release pill or capsule before swallowing, sniffing, or injecting the drug; or when they combine opioids with central nervous system depressants, such as alcohol, Valium, or Xanax.

• Central nervous system (CNS) depressants slow down activity in the brain. These drugs increase the activity of gamma aminobutyric acid (GABA), a chemical that inhibits the activity of other brain cells. When GABA is increased, people can feel drowsy or calm, an effect that is helpful for those suffering from anxiety or sleep disorders. Too much GABA, though, is not a good thing. It can cause confusion and slowed breathing. Benzodiazepines and barbiturates are CNS depressant medications; and alcohol—although not a medication—is also a CNS depressant. Combining them can be very risky.

  Since CNS depressants work by slowing the brain’s activity, stopping their use suddenly after long-term use can cause seizures, because the brain cells become overactive. This reaction can be prevented when these medications are taken and stopped under a doctor’s care.

• Stimulants have chemical structures that are similar to certain key brain neurotransmitters, the chemicals that allow nerve cells to send messages to each other. Stimulants increase the levels of these chemicals in the brain and body. This can increase blood pressure and heart rate and open up the pathways of the respiratory system, which can increase alertness, attention, and energy.

  Again, too much of a good thing is not good. An overdose of stimulants can cause anxiety, panic, tremors, irregular heartbeat, dangerously high body temperatures, and even heart attack. People who stop taking stimulants after some time may suffer from fatigue and depression because the brain adapts and decreases its natural response to the brain chemicals that stimulants resemble.

Aren’t Prescription Drugs Safer Than Illegal Drugs, Such as Cocaine or Heroin?

Many people think that abusing prescription drugs is safer than abusing illicit drugs like heroin because the manufacturing of prescription drugs is regulated or because they are prescribed by doctors. That’s true, but it doesn’t mean that these drugs are safe for someone who was not prescribed the drug or when they are taken in ways other than as prescribed.

Prescription drugs can have powerful effects in the brain and body, and they act on the same brain sites as illicit drugs. Opioid painkillers act on the same sites in the brain as heroin; prescription stimulants have effects in common with cocaine. And people sometimes take the medications in ways that can be very dangerous in both the short and long term (e.g., crushing pills and snorting or injecting the contents). Also, abusing prescription drugs is illegal—and that includes sharing prescriptions with friends.

Why Don’t People Who Take Prescription Drugs for Medical Conditions Become Addicted?

On rare occasions they do, which is why a person must be under a doctor’s care while taking prescription medications and sometimes when stopping their use. A doctor prescribes a medication based on an individual’s need—each patient is examined for symptoms and receives a dose of medication that will treat the problem effectively and safely. Typically, prescription drugs are taken in a form (e.g., a pill) that doesn’t allow for rapid absorption of the drug by the brain and at a dosage that treats the problem but doesn’t overwhelm the system—both of which reduce the likelihood of addiction.

Long-term medical use of certain prescription drugs can, however, lead to "physical dependence," because the brain and the body naturally adapt to chronic drug exposure. A person may need larger doses of the drug to achieve the same initial effects (tolerance), and when drug use is stopped, withdrawal symptoms can occur. Dependence is not the same as addiction. It is one of the many reasons why prescription drugs need to be taken and stopped under a physician's guidance.

What About Over-the-Counter Drugs, Like Cough Medicine? Aren’t They Safer Than Prescription Drugs?

Cough and cold medications are some of the most commonly abused over-the-counter (OTC) medications. Many contain an ingredient called dextromethorphan (DXM). However, to get the "high" or "dissociative" state craved by people who use drugs, large quantities are needed. At high doses, DXM causes effects similar to that of the drugs ketamine or PCP by affecting similar sites in the brain. Ketamine and PCP are considered "dissociative" drugs, which make people feel disconnected from their normal selves. They affect memory, feelings, and thoughts. DXM is similar, and its abuse can affect control over movement; cause numbness, nausea, and vomiting; and can increase heart rate and blood pressure.

When taken as directed, OTCs are safe and effective, but high doses can cause problems. And, some OTC medications can produce dangerous health effects when taken with alcohol. It is important to understand these risks, read the bottle labels, and take OTC medications only as directed.

Is Anyone Who Uses Prescription Drugs at Risk for Addiction? How Can I Protect Myself?

No, not all prescription drugs have the potential for abuse and addiction—many drugs don’t even act in the brain. For example, antibiotics, which are used for infections, are not addictive.

You (and your parents) should read the information that comes with the prescription and that is written on the container. This will include the doctor's instructions for how much of the drug to take and how often, as well as warnings about possible side effects. Read the label and learn whether you should take the drug with or without food, whether the drug will make you drowsy, and whether you can take it with other prescription or over-the-counter medicines. You can protect yourself by taking prescription drugs only according to these instructions. That includes the dosage prescribed and the length of time. If you have a question about a drug that has been prescribed for you, have your parents call your doctor or pharmacist.

If the drug is creating problems for you (e.g., if you experience unpleasant side effects or think you may be becoming addicted), you should consult with your doctor immediately to see if a change in dosage or scheduling of the medication is needed, or if it should be stopped altogether. But do not make these decisions on your own—there can be risks to changing dosage or stopping a medication abruptly.

What Can I Do To Help Someone I Suspect Is Abusing Prescription Drugs?

When someone has a drug problem, it’s not always easy to know what to do. If you are concerned about someone’s drug use (illicit or prescription), encourage him or her to talk to a parent, school guidance counselor, or other trusted adult. There are also anonymous resources, such as the National Suicide Prevention Lifeline (1-800-273-TALK) and the Treatment Referral Helpline (1-800-662-HELP).

The National Suicide Prevention Lifeline (1-800-273-TALK) is a crisis hotline that can help with many problems, not just suicide. This includes problems due to drug use. Family and friends who are concerned about a loved one or anyone interested in mental health treatment referrals can call this Lifeline. Callers are connected with a professional nearby who will talk with them about what they’re feeling or about concerns for family and friends.

In addition, the Treatment Referral Helpline (1-800-662-HELP)—offered by the Substance Abuse and Mental Health Services Administration—refers callers to treatment facilities, support groups, and other local organizations that can provide help for their specific needs. You can also locate treatment centers in your state by going to www.findtreatment.samhsa.gov.

Resource Materials

1.	National Institute on Drug Abuse. NIDA InfoFacts: Prescription and Over-the-Counter Medications (http://www.nida.nih.gov/Infofacts/ PainMed.html). Published June 2009. Retrieved February 2012.
2.	National Institute on Drug Abuse. NIDA Research Report—Prescription Drugs: Abuse and Addiction (http://www.drugabuse.gov/ResearchReports/Prescription/ Prescription.html). NIH Publication No. 11-4881. Published July 2001. Revised October 2011. Retrieved February 2012.
3.	National Institute on Drug Abuse. NIDA InfoFacts: Stimulant ADHD Medications—Methylphenidate and Amphetamines (http://www.nida.nih.gov/Infofacts/ADHD.html). Revised June 2009. Retrieved February 2012.
4.	National Institute on Drug Abuse. Monitoring the Future. National Results on Adolescent Drug Use. Overview of Key Findings 2011 (http://monitoringthefuture.org/pubs/monographs/mtf-overview2011.pdf). Bethesda, MD: NIDA, NIH, DHHS. Printed February 2012. Retrieved February 2012.

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This page was last updated in March 2012.