Review of mescaline studies finds too little good evidence for psychiatric use

The question

What does the published literature actually show about using mescaline, the main active compound in peyote and San Pedro cactus, for psychiatric conditions, and what side effects are reported?

What they did

Researchers searched four large research databases (PubMed, Scopus, Embase and Cochrane) for studies containing patient data on mescaline, primary accounts of its traditional medicinal use, and a range of psychiatric conditions. Animal studies, unpublished work and papers without an English full text were excluded. They screened 2,770 references, of which 66 met the inclusion criteria and only 10 were judged suitable for analysis. They also used a statistical method called Bayesian analysis to look at how often particular effects were reported.

What they found

The studies that were analyzed reported therapeutic effects including improvements on depression scales, improvements in well-being, and reductions in nicotine dependence, alcohol use and obsessions. Physical effects reported frequently included high blood pressure, headache, nausea and vomiting. The authors concluded the existing literature is limited and of highly variable quality, which prevented any firm conclusions about how common the psychological or physical effects of mescaline and mescaline-containing plants actually are.

The fine print

Only 10 studies could be analyzed out of 2,770 records screened, and the review itself describes their quality as highly variable. The abstract gives no participant numbers, doses, effect sizes or follow-up times, so the size and durability of any reported benefit is unknown. Non-English publications were excluded, which may have left out relevant traditional-use records. This summary is based on the abstract only.

What it means

Despite centuries of traditional use, there is currently very little reliable clinical research on mescaline, and the available reports are too sparse and uneven to say whether it helps or how safe it is.

Evidence grade: Very low. A systematic review that found only 10 analyzable studies of limited and highly variable quality, with no pooled controlled-trial data reported.

This summary is based on the study’s published abstract.