A very old drug, a very recent legal status
Humans have almost certainly used psilocybin-containing mushrooms for thousands of years across multiple cultures, including documented ritual use in Mesoamerica. Western science identified the active compound after Swiss chemist Albert Hofmann — the same chemist behind LSD — isolated psilocybin in 1958 from mushroom samples brought back from Mexico. Like LSD, it saw a burst of legitimate psychiatric research in the 1950s and '60s, then fell under the same Schedule I ban in 1970, halting formal research for roughly three decades.
The current legal and clinical picture
Psilocybin is now in one of the fastest-moving positions of any drug in this category. In the United States, Oregon became the first state to legalize supervised, licensed psilocybin services in 2020, followed by Colorado in 2022; New Mexico passed a medical psilocybin law in 2025, and its program, which the state aims to open by 31 December 2026, was still in rulemaking in October 2026. Oregon's service centers have served well over 10,000 clients since opening in 2023 (the Oregon Health Authority publishes quarterly figures), and Colorado's first licensed healing centers opened in 2025. It remains Schedule I federally, which means insurance doesn't cover state-legal sessions and it's still fully illegal outside those specific state programs. On the clinical-trial side, COMPASS Pathways' psilocybin formulation (COMP360) has produced two positive Phase 3 trials for treatment-resistant depression. In April 2026 the FDA agreed to review its new-drug application on a rolling basis and awarded it a Commissioner's National Priority Voucher, which can shorten review to a month or two. As of August 2026, the company expected to finish submitting in the fourth quarter of 2026 and to launch in the first half of 2027 — if the FDA approves it and the DEA reschedules the drug. (An LSD-based drug has since reported positive Phase 3 results too, but its developer plans to apply only in 2027, so psilocybin is currently first in line; see the LSD piece.)
What the risk profile actually looks like
By the numbers, psilocybin mushrooms scored the lowest of all 20 drugs in the best-known published harm comparison (Nutt and colleagues, 2010, covered in this category's opening piece): 6 out of 100, just below LSD's 7, and far below alcohol (72), tobacco (26) and cannabis (20). (Several substances in this category, such as DMT and ayahuasca, weren't part of that study.) There's no evidence of physical organ damage from typical use, no established fatal overdose from psilocybin's own toxicity, and it isn't associated with the kind of physical addiction or dependence seen with opioids, alcohol, or nicotine — tolerance actually builds so fast with repeated daily use that compulsive use is largely self-limiting.
That low score doesn't mean no risk. The real dangers are the same category as LSD's, and worth taking just as seriously:
Psychological crisis and setting. An unsupervised, unprepared "bad trip" can be genuinely frightening and, in rare cases, contribute to accidents from impaired judgment. This is exactly why clinical and legal therapeutic models insist on a trained facilitator, a prepared setting, and integration support afterward, rather than treating the substance alone as the whole intervention.
Psychosis risk in vulnerable individuals. As with LSD, a personal or family history of psychosis or schizophrenia is a serious red flag; psilocybin can trigger or unmask psychotic symptoms in people predisposed to them.
Misidentification. A genuinely underrated real-world danger: foraging wild mushrooms without expert identification carries a real risk of accidentally consuming a toxic, non-psychoactive lookalike species, some of which cause severe liver damage or death. This risk has nothing to do with psilocybin's own pharmacology and everything to do with mushroom identification — a distinct hazard worth flagging on its own.
Psilocybin's low toxicity score is one of the best-supported facts in this entire category. It is not the same claim as "safe under any conditions" — the setting, the support, and who's taking it still matter enormously.
The benefit side: what the research actually shows
Beyond the two positive Phase 3 trials for treatment-resistant depression, psilocybin-assisted therapy has shown promising results in smaller trials for end-of-life anxiety and depression in cancer patients, and for tobacco and alcohol use disorders — in each case using a small number of high-dose sessions paired with structured psychological preparation and integration, not a take-home prescription. Many participants in these trials, and many recreational users, report the experience as among the most personally meaningful of their lives — a subjective finding that researchers now take seriously as a possible mechanism, not just a side effect, of the drug's therapeutic potential.
Try this
If you're curious about the actual scale of the current legal shift, look up how many licensed psilocybin service centers currently operate in Oregon and Colorado combined — the number has grown fast enough that most people are surprised by how real and operational this has already become, years before any federal approval.
The takeaway
Psilocybin mushrooms have likely been used by humans for millennia, were scientifically isolated in 1958, banned alongside LSD in 1970, and are now further along the FDA's approval process than any other classic psychedelic — legal for supervised use in Oregon and Colorado (New Mexico's medical program is due to open by the end of 2026), with FDA approval possible in 2027. They scored the lowest of the 20 drugs in the best-known harm comparison, with very low physical toxicity and addiction potential, but carry real psychological risks — a severe crisis in the wrong setting, a serious risk in anyone predisposed to psychosis, and an entirely separate risk of misidentifying toxic lookalike mushrooms when foraging.
Try this: look up current data on Oregon's and Colorado's licensed psilocybin service centers to see how far this legal shift has already gone.
Sources & Further Reading
Sources
- Historical and cultural use, and Hofmann's 1958 isolation of psilocybin, reflect standard ethnobotanical and chemical-history documentation.
- The 1970 Schedule I classification and its effect on research reflect documented U.S. drug-policy history.
- State legalization status: Oregon Health Authority, Oregon Psilocybin Services data dashboard (quarterly; 1,509 clients in the first quarter of 2025 alone); New Mexico Department of Health, Center for Medical Cannabis and Psilocybin, and Source NM reporting (August 2026) on the program's rollout.
- Clinical and regulatory status: Compass Pathways, second-quarter 2026 results (SEC Form 8-K, 5 August 2026) and its April 2026 announcement of FDA rolling review and a Commissioner's National Priority Voucher.
- Comparative harm scoring reflects Nutt DJ, King LA, Phillips LD, "Drug harms in the UK," The Lancet, 2010.
Go deeper
- 🌐 Search "COMPASS Pathways psilocybin Phase 3 results" for the current clinical trial data
- 🌐 DanceSafe.org — harm-reduction guidance, including mushroom misidentification risks
- 🌐 Related pieces in this library: The Real Harm Ladder and LSD, this category