Illegal drugs are those that are not prescribed by a doctor or bought at a drugstore. They are sometimes also called "street drugs."

Some examples of illegal drugs include heroin (a narcotic); cocaine (a stimulant); LSD, mescaline, PCP, methamphetamine, and psilocybin (hallucinogens); marijuana and hashish (cannabis); and gamma-hydroxybutyrate (GHB). Although GHB is legal in Europe for anesthetic uses and in the United States for government-approved clinical trials for treating narcolepsy, it has been otherwise illegal in the United States since 1990.

The effects of illegal drugs can be unpredictable because:

  • Most drugs are very addictive.
  • People respond differently to the same drugs.
  • The strength or potency of the drug may be uncertain.
  • They may contain unknown or unexpected substances. There is no quality control for street drugs like that required for prescription drugs.
  • They may interact with other drugs or alcohol in unpredictable ways.

Current as of: February 20, 2015

Author: Healthwise Staff

Medical Review: William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine