Mescaline vs Psilocybin

Urgent first. For a medical emergency or suspected poisoning, call 911 or US Poison Help at 1-800-222-1222. In the US, call or text 988 for a mental health crisis.

This page is education only. It gives no amounts, no equivalence between mescaline and psilocybin, and no information on finding, preparing or identifying cacti or fungi.

Different origins and chemistry

Mescaline (3,4,5-trimethoxyphenethylamine) is a naturally occurring alkaloid found in cacti, mainly the peyote cactus (Lophophora williamsii) and cacti of the genus Echinopsis. [1] NIDA notes it can also be lab-made. [2] Psilocybin is a compound from certain mushrooms. [2] Psilocybin is a tryptamine and a prodrug that the body turns into psilocin. [3][4] Mescaline is a phenethylamine derivative with signs consistent with a sympathomimetic effect, and it is largely excreted unchanged in human urine. [5][6]

Both are described as acting mainly at the serotonin 5-HT2A receptor. [6][4] This is one shared feature, not proof that effects are identical.

The direct comparison

Evidence level: one randomized, double-blind, placebo-controlled crossover trial in 32 healthy participants, comparing mescaline, LSD and psilocybin. [7]

Limits: healthy adults, a controlled setting, study-specific amounts, short follow-up. The durations belong to those amounts and do not apply to any cactus or mushroom product.

Treatment evidence

Evidence labels: promising but limited (psilocybin in depression), insufficient evidence (mescaline).

NIDA reports Breakthrough Therapy designation by FDA for two psilocybin formulations being studied for depression, which is not an approval. [2] For mescaline, a review concluded that its ability to help overcome alcoholism and improve mental well-being makes it potentially beneficial, but that is a reviewers' conclusion; we found no modern controlled trials of mescaline for these uses in the sources read. [1] Reviewers also note research on mescaline has been limited since the early 1970s. [1]

Risks

For mescaline, a toxicology review found most intoxications mild, addiction and dependence practically absent, and exposure rarely confirmed by testing. [5] For psilocybin, a meta-analysis of therapeutic-dose trials found headache, nausea, anxiety, dizziness and raised blood pressure more common than with comparators. [8] Across classic psychedelics, serious adverse events were reported in about 4% of participants with pre-existing neuropsychiatric disorders and none in healthy participants. [9] Safety in pregnancy is unknown for both; NIDA says there are no safety data for psilocybin in pregnancy. [2]

Culture and conservation

Peyote has a long history of use: archaeological evidence dates back more than 5,000 years. [10] Peyote has also been described as threatened, and the Native American Church context matters. [11] See peyote conservation and peyote and its traditional contexts. Psilocybin is not a substitute for a tradition either.

Legal status

Not legal advice; laws change. In the United States, 21 CFR 1308.11 lists mescaline, peyote and psilocybin in Schedule I (eCFR, read 2026-10-22). [12] A separate rule says the peyote listing does not apply to the nondrug use of peyote in bona fide Native American Church religious ceremonies. [13] Other countries: not verified. See psychedelic legal status by country.

No winner

For each alone see mescaline and psilocybin.