Contact high

Contact high is a phenomenon that occurs in otherwise sober people who experience a drug-like effect just by coming into contact with someone who is under the influence of a psychoactive drug. In a similar way to the placebo effect, a contact high may be caused by classical conditioning as well as by the physical and social setting.

A 1970s glossary of drug users' language describes a contact high as "a psychogenic 'trip' without taking drugs, by being close to somebody while he is on drugs". The term is sometimes incorrectly used to describe the high experienced by a person who has inhaled secondhand marijuana smoke.

In Alexander Shulgin's book PiHKAL under the 2C-I entry, a notable reaction was observed in a participant who took a placebo while in an environment with other people who are under the influence of a drug. The participant wrote that he had "absorbed the ambience of the folks who had actually imbibed the material."