Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia and as a treatment for depression and pain management. Ketamine is an NMDA receptor antagonist, which accounts for most of its psychoactive effects.
Ketamine is used as a recreational drug for its hallucinogenic and dissociative effects. When used recreationally, it is found both in crystalline powder and liquid form, and is often referred to by users as "Special K" or simply "K". When used recreationally, ketamine produces a dissociative state, characterised by a sense of detachment from one's physical body and the external world which is known as depersonalization and derealization. At sufficiently high doses, users may experience what is called the "K-hole", a state of dissociation with visual and auditory hallucinations.
Recreational use of ketamine was documented in the early 1970s in underground literature (e.g., The Fabulous Furry Freak Brothers). It was used in psychiatric and other academic research through the 1970s, culminating in 1978 with the publishing of psychonaut John Lilly's The Scientist, and Marcia Moore and Howard Alltounian's Journeys into the Bright World, which documented the unusual phenomenology of ketamine intoxication. The incidence of non-medical ketamine use increased through the end of the century, especially in the context of raves and other parties. Its emergence as a club drug differs from other club drugs (e.g., MDMA), however, due to its anesthetic properties (e.g., slurred speech, immobilization) at higher doses.