Risk assessment of ritual use of oral dimethyltryptamine (DMT) and harmala alkaloids

A systematic review and interviews with ceremony participants assessed the acute toxicity and psychological risks of ayahuasca, a brew containing dimethyltryptamine (DMT) and β‐carbolines used in religious ceremonies. No animal models tested ayahuasca's acute toxicity or abuse potential, but separate studies of DMT and harmala alkaloids suggest a lethal human dose is probably over 20 times a typical ceremonial dose. Adverse effects may occur with casual use, especially alongside serotonergic substances. DMT can cause aversive reactions or transient psychotic episodes that resolve within hours. There is no evidence of substantial abuse potential, and long-term psychological benefits are documented when used in a well-established social context. The safety margin is comparable to codeine, mescaline, or methadone.

Study at a glance

Abstract

ABSTRACT Aim To extend previous reviews by assessing the acute systemic toxicity and psychological hazards of a dimethyltryptamine and β‐carboline brew (ayahuasca/hoasca) used in religious ceremonies. Method A systematic literature search, supplemented by interviews with ceremony participants. Results No laboratory animal models were located that tested the acute toxicity or the abuse potential of ayahuasca. Separate animal studies of the median lethal dose of dimethyltryptamine (DMT) and of several harmala alkaloids indicated that a lethal dose of these substances in humans is probably greater than 20 times the typical ceremonial dose. Adverse health effects may occur from casual use of ayahuasca, particularly when serotonergic substances are used in conjunction. DMT is capable of inducing aversive psychological reactions or transient psychotic episodes that resolve spontaneously in a few hours. There was no evidence that ayahuasca has substantial or persistent abuse potential. Long‐term psychological benefits have been documented when ayahuasca is used in a well‐established social context. Conclusion A decoction of DMT and harmala alkaloids used in religious ceremonies has a safety margin comparable to codeine, mescaline or methadone. The dependence potential of oral DMT and the risk of sustained psychological disturbance are minimal.