3,4-Methyl​enedioxy​methamphetamine (MDMA), commonly known as ecstasy, and molly or mandy, is a potent empathogen–entactogen with stimulant and minor psychedelic properties. Investigational indications include as an adjunct to psychotherapy in the treatment of post-traumatic stress disorder (PTSD) and social anxiety in autism spectrum disorder. The purported pharmacological effects that may be prosocial include altered sensations, increased energy, empathy, and pleasure. When taken by mouth, effects begin in 30 to 45 minutes and last three to six hours.

Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary mental states and an apparent expansion of consciousness. Also referred to as classic hallucinogens or serotonergic hallucinogens, the term psychedelic is sometimes used more broadly to include various types of hallucinogens, such as those which are atypical or adjacent to psychedelia like salvia and MDMA, respectively.