psilocybin
(SY-loh-SY-bin)
A substance being studied in the treatment of anxiety or depression in patients with advanced cancer. It is taken from the mushroom Psilocybe mexicana. Psilocybin acts on the brain to cause hallucinations (sights, sounds, smells, tastes, or touches that a person believes to be real but are not real). Also called psilocybine.