Are there long-term dangers to drinking ayahuasca?

There is a popular idea that repeated use of psychedelics over years will leave you 'fried', mentally impaired and out of touch with reality. Contrary to this, any long-term ayahuasca-drinkers I have met seem to have some indefinable human quality about them, a sort of glow and optimism. It's something that you are familiar with if you have hung around people who have done other mystical disciplines like yoga for many years.

I don't know what makes the difference between ayahuasca-drinkers and 'acid casualties'. It could be that ayahuaca is more benign, but seeing as no psychedelic can be linked to brain damage, it seems more likely that the benefits come from the supportive, ceremonial set-and-setting around ayahuasca-drinking.

A few scientific studies have investigated long-term effects of ayahuasca -

A 1999 study called 'Do hallucinogens cause residual neuropsychological toxicity?' concludes that "the literature tentatively suggests that there are few, if any, long-term neuropsychological deficits attributable to hallucinogen use."

A 2008 paper by the same author called 'Evidence of health and safety in American members of a religion who use a hallucinogenic sacrament' interviewed 32 ayahuasca drinkers. They had consumed ayahuasca between 20 and 1300 times and the researchers were not able to find any evidence of damage.

'Risk assessment of ritual use of oral dimethyltryptamine (DMT) and harmala alkaloids' is a systematic search of all the scientific literature about ayahuasca and DMT, especially looking at studies when animals were given these drugs over long periods of time. It was found that none of these studies found long-term damage.

Ayahuasca as a psychedelic for modern times

Ayahuasca is an interesting case. Whereas psilocybin and LSD became known in the West in the first half of the 20th century, and went through the excesses and backlash of the hippie movement, ayahuasca was a later arrival on the scene. As a result, it never had its reputation tarnished in quite the same way. Ayahuasca has never been abused much and has not been much used outside of its traditional context for healing and vision-seeking. This has given it a more 'legitimate' aura than other psychedelics. In my personal experience, whereas many old acidheads bear obvious damage from poorly-controlled experiences, long-time ayahuasca drinkers have that undefinable yet unmistakable human glow that comes from proper and fruitful investigation of one's mind and consciousness. This is weak anecdotal evidence and I do not expect it will convince anyone, but I know its truth for myself.

Several progressive researchers in psychology have recognized the unique position that ayahuasca holds in this regard.

Kenneth W. Tupper wrote a paper called The Globalization of Ayahuasca: Harm Reduction or Benefit Maximization?, in which he points out that in the South American cultures familiar with it, ayahuasca has always held a social role as a healer and teacher, never as a substance associated with criminality, recklessness or risk-taking, like the social role given to most psychoactives in the West. The question is - as ayahuasca enters Western culture, which role will it be given?

Jordi Riba, who did his PhD thesis on ayahuasca, published a paper in 2005 along with Manel Barbanoj titled, Bringing Ayahuasca to the Clinical Research Laboratory. They summarize their findings of 7 years of research into the pharmacology and physiology of ayahuasca, and give groundrules for good scientific research to be done on it. Although the paper considers ayahuasca as a scientific research tool rather than a healing agent, this is because they know that the scientific research must be very solid before clinical use can go ahead.

Also in 2005, the inimitable and controversial Dennis McKenna wrote Ayahuasca and Human Destiny. This short essay is a curious bridge between scientific research and hippie rhapsody.

And suddenly, and literally, “out of the Amazon,” one of the most impacted parts of our wounded planet, ayahuasca emerges as an emissary of trans-species sentience, to bring this lesson: You monkeys only think you’re running things. In a wider sense, the import of this lesson is that we need to wake up to what is happening to us and to the planet. We need to get with the program, people. We have become spiritually bereft and have been seduced by the delusion that we are somehow important in the scheme of things. We are not.

Overall, there does seem to be a promising trend in which ayahuasca is slowly, cautiously taking steps towards becoming to Western culture what it has been to Amazonian culture: a healer, a teacher and a wise counsellor. This process must happen slowly, lest another anti-drug backlash condemn ayahuasca to the filthy fate of other mind-altering drugs.