Ayahuasca is a South American psychoactive brew, traditionally used by Indigenous cultures and folk healers in the Amazon and Orinoco basins for spiritual ceremonies, divination, and healing a variety of psychosomatic complaints. Originally restricted to areas of Peru, Brazil, Colombia and Ecuador, in the middle of the 20th century it became widespread in Brazil in the context of the appearance of syncretic religions that use ayahuasca as a sacrament, like Santo Daime, União do Vegetal and Barquinha, which blend elements of Amazonian Shamanism, Christianity, Kardecist Spiritism, and African-Brazilian religions such as Umbanda, Candomblé and Tambor de Mina, later expanding to several countries across all continents, notably the United States and Western Europe, and, more incipiently, in Eastern Europe, South Africa, Australia, and Japan.

A psychoactive drug, psychopharmaceutical, psychoactive agent, or psychotropic drug is a chemical substance that changes the function of the nervous system and results in alterations of perception, mood, cognition, and behavior. These substances have various applications, including medical use like psychedelic therapy, recreationally, or for spiritual reasons. Some categories of psychoactive drugs may be prescribed by physicians and other healthcare practitioners because of their therapeutic value.