A person who regularly uses drugs for non-medical purposes.
The use of illegal drugs or the use of a legal drug in excessive quantities or for purposes other than those for which it is normally intended. Commonly abused illegal drugs include cannabis (marijuana; hashish; THC, or delta-9-tetrahydrocannabinol), narcotics (heroin, morphine, methadone, codeine), cocaine, amphetamines (“speed”), hallucinogens (PCP, or “angel dust”; LSD, or lysergic acid diethylamide; psilocybin; mescaline), and inhalants (model glue, spray paint, gasoline, aerosol propellants. Legal prescription drugs, such as painkillers, tranquilizers, benzodiazepines, chloral hydrate, barbiturates, and preparations containing hydrocodone, can also be abused. Legal over-the-counter medications and products, including laxatives, nasal sprays, cough medicine, alcohol, and tobacco, can be abused as well.
The use or overuse, usually by self-administration, of any drug in a manner that deviates from the prescribed pattern.