Phencyclidine (PCP) is a mind-altering drug that may lead to hallucinations (a profound distortion in a person’s perception of reality). It is considered a dissociative drug, leading to a distortion of sights, colors, sounds, self, and one's environment. PCP was developed in the 1950s as an intravenous anesthetic, but due to the serious neurotoxic side effects, its development for human medical use was discontinued. Ketamine (Ketalar), an anesthetic used for surgery and painful procedures was developed instead and is structurally similar to PCP.

In its purest form, PCP is a white crystalline powder that readily dissolves in water or alcohol and has a distinctive bitter chemical taste. On the illicit drug market, PCP contains a number of contaminants causing the color to range from a light to darker brown with a powdery to a gummy mass consistency.