Recreational drug use is the use of a psychoactive drug (legal, controlled, or illegal) to alter one's mental state through changes to the central nervous system that create positive emotions and feelings. When a substance enters the user's body, it brings on an intoxicating effect, often referred to as a "high". In popular usage, it is generally considered to be a tolerated social behaviour rather than a serious medical conditions such as self-medication.

Drugs commonly considered capable of recreational use include alcohol, marijuana, nicotine, caffeine, and some controlled substances within the scope of the United Nations' Single Convention on Narcotic Drugs and Convention on Psychotropic Substances. In 2009 it was estimated that about 3% to 6% of people aged 15 to 65 had used illegal drugs at least once (149 to 270 million).[1] International and domestic law enforcement agencies are perpetually occupied with interdiction efforts against illegal drug use, manufacture, and distribution.