PCP (phencyclidine) was originally developed in the 1950s as a general anesthetic because it provided strong pain relief without significantly depressing breathing or heart function.(Source) It was marketed under the brand name Sernyl and used in human surgery in the early 1960s.(Source) However, doctors soon observed that many patients experienced severe post-operative agitation, confusion, and psychotic reactions, so PCP was discontinued for human medical use and restricted to veterinary applications.(Source)

By the late 1960s and 1970s, PCP began appearing as an illicit street drug, often associated with high-risk behavior and violent or unpredictable reactions.(Source) Many of its street names—such as hog, horse tranquilizer, and elephant—come from its history in veterinary medicine.

PCP is a dissociative hallucinogen, meaning it alters perception, mood, and awareness while creating a sense of detachment from one’s body or surroundings.(Source) It primarily blocks the N-methyl-D-aspartate (NMDA) receptor for glutamate, a neurotransmitter involved in pain perception, learning, memory, and emotional processing.(Source) PCP also affects dopamine, norepinephrine, and serotonin systems, which can contribute to euphoria, agitation, or mood changes.(Source)

PCP is usually found as a white or off-white crystalline powder that can be pressed into tablets, filled into capsules, or dissolved in liquid. A typical illicit dose is often reported in the range of 5–10 milligrams, although street products are highly variable in strength.(Source) Effects can begin within minutes when smoked or vaped, or within 30–60 minutes when taken orally, and may last 4–6 hours, with some psychological effects persisting up to 24 hours or longer.(Source)

Because PCP is unpredictable and frequently mixed with other substances, any use carries significant risk—even for people who have used it before.