Ayahuasca

South American psychoactive decoction

Ayahuasca is a South American psychoactive decoction prepared from Banisteriopsis caapi vine and a dimethyltryptamine (DMT)-containing plant, used by Indigenous cultures in the Amazon and Orinoco basins as part of traditional medicine and shamanism. The word ayahuasca, originating from Quechuan languages spoken in the Andes, refers both to the B. caapi vine and the psychoactive brew made from it, with its name meaning 'spirit rope' or 'liana of the soul'.

The specific ritual use of ayahuasca was widespread among Indigenous groups by the 19th century, though its precise origin is uncertain. Ayahuasca is traditionally prepared by macerating and boiling B. caapi with other plants like Psychotria viridis during a ritualistic, multi-day process. Ayahuasca has been used in diverse South American cultures for spiritual, social, and medicinal purposes, often guided by shamans in ceremonial contexts involving specific dietary and ritual practices, with the Shipibo-Konibo people playing a significant historical and cultural role in its use. Originally confined to regions of Peru, Brazil, Colombia, and Ecuador, ayahuasca became widespread in Brazil, expanding widely by the mid-20th century through syncretic religions in Brazil. In the late 20th century, ayahuasca use expanded beyond South America to Europe, North America, and elsewhere, leading to legal cases, non-religious adaptations, and the development of ayahuasca analogues (i.e., variants) using local or synthetic ingredients.

While DMT is internationally classified as a controlled substance, the plants containing it—including those used to make ayahuasca—are not regulated under international law, leading to varied national policies that range from permitting religious use to imposing bans or decriminalization. The United States patent office controversially granted, challenged, revoked, reinstated, and ultimately allowed to expire a patent on the ayahuasca vine, sparking disputes over intellectual property rights and the cultural and religious significance of traditional Indigenous knowledge.

Ayahuasca produces intense psychological and spiritual experiences with potential therapeutic effects. Ayahuasca's psychoactive effects primarily result from DMT, rendered orally active by harmala alkaloids in B. caapi, which act as reversible inhibitors of monamine oxidase; B. caapi and its β-carbolines also exhibit independent contributions to ayahuasca's effects, acting on serotonin and benzodiazepine receptors. Higher doses of ayahuasca or harmala alkaloids may increase risks.