The most authentic depiction of Ayahuasca culture I've seen so far! -ed.
Shamanism - Other Worlds - Ayahuasca Documentary
Ayahuasca is used largely as a religious sacrament. Those whose usage of ayahuasca is performed 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 Peruvian Amazonia. The religion Santo Daime uses it.
While non-native users know of the spiritual applications of ayahuasca, a less well-known traditional usage focuses on the medicinal properties of ayahuasca. Its purgative properties are highly important (many refer to it as la purga, "the purge"). The intense vomiting and occasional diarrhea it induces can clear the body of worms and other tropical parasites, and harmala alkaloids themselves have been shown to be anthelmintic.
Thus, this action is twofold; a direct action on the parasites by these harmala alkaloids (particularly harmine in ayahuasca) works to kill the parasites, and parasites are expelled through the increased intestinal motility that is caused by these alkaloids.