The Health Effects of Commonly Used Drugs

All drug abuse can affect your health

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One of the myths floating around about drugs is if a particular substance can be used as a medication, it's not harmful. Contrary to what some believe, the abuse or nonmedical use of any drug can have potentially long-lasting effects on your health.

The truth is even the "safest" drugs can have negative effects on your health and well-being if they are used too often or over too long a period of time.

Besides alcohol (which has its own set of health effects), the following are the most commonly abused drugs in the United States, in order of popularity, and how they can affect your health.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.


Marijuana is the most commonly used illicit drug in the United States. When smoked, it begins to affect users almost immediately and can last for one to three hours. Users claim that smoking marijuana is not harmful, but scientific evidence proves otherwise.

Prescription Drugs

According to the National Survey on Drug Use and Health (NSDUH), after marijuana, the most popular drugs of abuse in the U.S. include pain relievers, tranquilizers, stimulants, and sedatives. This involves the nonmedical use of prescription drugs, over-the-counter drugs, and drugs that may be manufactured illegally, such as methamphetamine and ecstasy.

Cocaine and Crack Cocaine

Approximately 2.1 million people in the U.S. use cocaine, making it the third most abused category of drug. Cocaine can be snorted, injected and even smoked in some forms of the drug. In all cases, cocaine is a strong central nervous system stimulant which affects the brain.


Each month, more than a million people in the U.S. use hallucinogens such as LSD, PCP, Ketamine, and DXM, according to NSDUH. Hallucinogens disrupt a person's ability to think and communicate rationally, or even to recognize reality, sometimes resulting in bizarre or dangerous behavior.


Of all the illicit drugs available on the market today, heroin is the least commonly abused, with only an estimated 200,000 current users in the United States. That's probably because it is the most addictive of all the street drugs. Whether injected, snorted or smoked, heroin will begin to affect the body's central nervous system almost immediately after it is used.

Has Your Health Been Affected?

If you believe that your health has been affected by your use of illicit drugs or nonmedical use of prescription or over-the-counter drugs, seek medical attention immediately. If you need help trying to stop taking drugs there are many help and support resources available.

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Buddy T
Buddy T is an anonymous writer and founding member of the Online Al-Anon Outreach Committee with decades of experience writing about alcoholism.