Ayahuasca is an entheogenic brew made out of Banisteriopsis caapi vine and other ingredients. The brew is used as a traditional spiritual medicine in ceremonies among the indigenous peoples of the Amazon basin. An entheogen is a class of psychoactive substances that induce any type of spiritual experience aimed at development.

B. caapi contains several alkaloids that act as monoamine oxidase inhibitors (MAOIs). Another common ingredient in ayahausca is the shrub Psychotria viridis which contains the primary psychoactive compound, dimethyltryptamine (DMT). MAOIs are required for DMT to be orally active.

Ayahuasca is used largely as a treasured sacrament. People who work with ayahuasca in non-traditional contexts often align themselves with the philosophies and cosmologies associated with ayahuasca shamanism, as practiced among indigenous peoples like the Urarina of the Peruvian Amazon.

While non-native users know of the spiritual applications of ayahuasca, a less well-known traditional usage focuses on the medicinal properties of ayahuasca. When used for its medicinal purposes, ayahuasca affects the human consciousness for less than six hours, beginning half an hour after consumption and peaking after two hours. In some cases, individuals experience significant psychological stress during the experience. Ayahuasca also has cardiovascular effects, moderately increasing heart rate and diastolic blood pressure. It is for this reason that extreme caution should be taken with those who may be at risk of heart disease.