Psilocybin Mushroom Chemistry and Research Limits

Safety first. If someone has eaten a mushroom and is confused, very agitated, vomiting repeatedly, has chest pain, a seizure or trouble breathing, call 911 or US Poison Help at 1-800-222-1222. See poisoning: what to do first.

This page explains what laboratory measurements of psilocybin mushrooms can and cannot tell us. It gives no dose guidance, no conversions between species or forms, and no "typical strength", because the research does not support one.

The compounds

Psilocybin, psilocin, baeocystin, norbaeocystin and aeruginascin are tryptamines, a family of compounds that resemble the brain chemical serotonin. Psilocybin and its active product psilocin are the best known. [1] After psilocybin is taken, the body converts it to psilocin. [2] For the difference between the two, see psilocybin vs psilocin.

These compounds typically occur in most species of the genus Psilocybe. [1] They are also found in some other fungi, because the genes for making psilocybin appear to have moved between fungal groups on several occasions. [3]

What measurements show

Laboratory studies report amounts as a share of weight or as an amount per gram. Each figure applies only to the sample that was tested. Four examples show the range of what has been published.

These numbers are not comparable with each other. They use different organisms or forms, fresh versus dried material, different methods and different units. Do not use them to estimate how strong any mushroom or product is.

Why amounts vary

• Between individual mushrooms. Even within one batch, the tryptamine content of individual fruiting bodies was highly variable. [1]
• Between batches. A 2026 study of uniformly prepared laboratory batches still found batch variability and recommended testing every batch. [7]
• Between strains and growth conditions. A review describes substantial variability between strains and within a strain, and says knowledge about how conditions affect psilocybin production is very limited. [8]
• With storage. Samples stored differently showed different tryptamine breakdown, and the ratio of psilocybin to psilocin varied among samples, which the authors link to possible effects of storage conditions. [1][6]
• With the part of the mushroom. In one study the stalks held about half the tryptamine amount found in the caps, but this difference was not statistically significant because of high variability between mushrooms. [1]

Research limits

Research on these fungi has been slowed by decades of legal restrictions. [8] Several limits follow.

• Few species studied. The psilocybin gene cluster is known for only five of about 165 Psilocybe species. [3]
• Measurement is hard. The authors of a 2025 method paper say that accurately measuring these compounds in fungal material remains analytically challenging. [6]
• Clinical trials use a pure compound. Clinical studies of psilocybin have so far administered the pure form, not whole mushrooms. [1] Findings from trials of synthetic psilocybin should not be assumed to apply to mushrooms or truffles. See psychedelic clinical trials and research limits.
• Fungal material is not standardized. Because of batch variability, the authors of a 2026 laboratory study recommend that each batch be tested for tryptamine content. [7]

Evidence labels used here

• Composition varies widely between samples: established in the sense that several independent laboratory studies report it. [1][6][7]
• A typical or average strength for a species or commercial name: Proper evidence not found. We looked at the studies above and a review of P. cubensis strains.
• Equivalence between species, forms or products: Proper evidence not found. We do not give conversions.

Related pages

For the genus, see psilocybin mushrooms. For names that appear on products, see commercial mushroom names and naming limits. For mislabeled products, see unverified mushroom gummies and similar products.