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Psilocybin research, told honestly
What clinical trials have found, what didn’t work, where approval stands, and the long history behind it. Each study links to its source.
Checked against the sources on November 7, 2026
Our products haven’t been studied or evaluated for any condition, and nothing here is medical advice.
First, two very different things
Almost every striking result below comes from supervised, high-dose sessions: one to three large doses of psilocybin, taken lying down in a calm room with trained guides, with preparation before and support after. That’s very different from microdosing, where people take a tiny amount at home.
Blinded microdosing studies so far haven’t beaten placebo on their main outcomes. We cover them on our microdosing page. This page is about the large-dose research.
What the trials found
All with psychological support, all in carefully screened volunteers. The limitations are part of the story, so they’re included.
Distress in people with life-threatening cancer
56 people with cancer and depressed mood or anxiety were randomized, and 51 completed at least one session. Each received a very low dose and, five weeks apart, a high dose (nearly always 22 mg per 70 kg of body weight). Five weeks after the first session, 92% of those given the high dose first had a clinically meaningful drop in depression, versus 32% of those given the low dose first. Six months on, 78% showed a clinically meaningful response for depression and 83% for anxiety.
Limits: the comparison was a low dose, not an inactive placebo; staff could often tell the doses apart; and the group was small and not very diverse. Blood pressure rose during some high-dose sessions, and some people felt sick.
Griffiths et al., J Psychopharmacol 2016;30(12):1181–1197. PubMed 27909165
The same question, a second team
29 people with cancer-related anxiety or depression received a single psilocybin dose or niacin (a vitamin that causes flushing), with psychotherapy, then switched after seven weeks. At seven weeks, 83% of the psilocybin-first group had a meaningful drop in depression versus 14% of the niacin-first group; for anxiety, 58% versus 14%.
Limits: the authors described niacin as a control with limited blinding, the group was small, and after the switch everyone had received psilocybin, so the long-term results have no comparison group.
Ross et al., J Psychopharmacol 2016;30(12):1165–1180. PubMed 27909164
Quitting smoking
15 long-time smokers had two or three psilocybin sessions (20 and 30 mg per 70 kg) inside a 15-week quit program with cognitive behavioral therapy. At six months, 12 of 15 (80%) were confirmed not smoking by lab tests. At 12 months it was 10 of 15, in a later follow-up (Johnson et al., 2017).
Limits: no control group and no blinding, so the effect can’t be separated from the therapy, expectations or who signed up.
Johnson et al., J Psychopharmacol 2014;28(11):983–992. PubMed 25213996
Alcohol use disorder
95 adults were randomized; all were offered 12 weeks of therapy, plus two medication sessions at weeks 4 and 8: psilocybin or an antihistamine (diphenhydramine) as the comparison. Over the 32 weeks after the first dose, heavy drinking days averaged 9.7% with psilocybin versus 23.6% with the comparison.
Limits: the blind didn’t hold: about 94% of participants guessed correctly which they’d had. Headaches were far more common with psilocybin (44% versus 4%).
Bogenschutz et al., JAMA Psychiatry 2022;79(10):953–962. PubMed 36001306
Major depression, one dose
104 adults with major depression received a single 25 mg dose of psilocybin or niacin, both with preparation, a supervised session and follow-up support. On a standard depression scale (MADRS), the psilocybin group improved by 12.3 points more at six weeks, and by 12.0 points more after one week. Sustained response was 41.7% versus 11.4%.
Limits: sustained remission wasn’t significantly different; blinding wasn’t checked; and headache (66% versus 24%) and nausea (48% versus 6%) were common.
Raison et al., JAMA 2023;330(9):843–853. PubMed 37651119
Treatment-resistant depression, three doses compared
233 adults whose depression hadn’t responded to other medicines received one dose of 25, 10 or 1 mg, with psychological support. At three weeks, the 25 mg group’s depression scores had fallen 6.6 points more than the 1 mg group’s. The 10 mg dose wasn’t significantly different from 1 mg.
What didn’t work, and the risks: the benefit didn’t clearly last to 12 weeks. 77% of people had side effects, most often headache, nausea and dizziness. Suicidal thoughts, suicidal behavior or self-injury were reported in all three groups. The three serious suicidal-behavior events were all in the 25 mg group, and serious self-injury happened in all three groups (ClinicalTrials.gov NCT03775200).
Goodwin et al., N Engl J Med 2022;387(18):1637–1648. PubMed 36322843
Psilocybin versus a common antidepressant
59 adults with long-standing depression received either two 25 mg psilocybin sessions or six weeks of the antidepressant escitalopram (that group also got two 1 mg psilocybin doses so no one knew their group). On the main depression measure, there was no significant difference between the two after six weeks.
Worth knowing: other measures generally leaned toward psilocybin, but those weren’t corrected for the many comparisons made, so they don’t settle anything. The trial didn’t show psilocybin to be better than escitalopram.
Carhart-Harris et al., N Engl J Med 2021;384(15):1402–1411. PubMed 33852780
The larger trials since
Compass Pathways reported that two Phase 3 trials of its psilocybin, COMP360, in treatment-resistant depression met their main goals. The differences from the comparison groups at six weeks were about 3.6 and 3.8 points on the MADRS scale: real, but much smaller than the Phase 2 figures often quoted.
Compass Pathways press release, February 17, 2026. Read the release
Where approval stands
As of November 7, 2026.
The FDA gave Breakthrough Therapy designations to Compass Pathways’ psilocybin program for treatment-resistant depression (October 2018) and to the Usona Institute’s for major depression (November 2019). A designation is meant to speed up development and review. It isn’t an approval, and it doesn’t show that something works.
On November 3, 2026, Compass said it would file the final part of its new drug application within two weeks and was preparing for a launch in the first half of 2027, subject to FDA approval. Because psilocybin is a Schedule I substance, an approved product would also need to be rescheduled by the DEA. No psilocybin medicine is approved today.
A long history
Centuries of ceremony, a few decades of science, a long pause, and a careful return.
- Before the 1950s
Mazatec healers in Oaxaca, Mexico, used mushrooms in night-long healing ceremonies called veladas.
- 1955 and 1957
The banker and amateur mycologist R. Gordon Wasson took part in a velada led by the Mazatec curandera María Sabina in Huautla de Jiménez, and described it in Life magazine on May 13, 1957, under the headline “Seeking the Magic Mushroom”. Life, May 13, 1957
- 1958
Albert Hofmann and colleagues at Sandoz in Switzerland isolated psilocybin from Psilocybe mexicana, grown in culture by the mycologist Roger Heim (PubMed 13537892), and reported its structure and synthesis the same year (PubMed 13609599). Psilocin was characterized in 1958 and 1959 (PubMed 13652944).
- The 1960s
Sandoz supplied psilocybin to researchers under the name Indocybin for psychological and clinical research. PubMed 29956917
- 1970
The Controlled Substances Act, signed on October 27, 1970, placed psilocybin and psilocin in Schedule I, and research nearly stopped. The Act, 84 Stat. 1236
- 2000 to 2019
Johns Hopkins says it was the first US team to win regulatory approval, in 2000, to restart this research in healthy volunteers. Its landmark paper followed in 2006 (PubMed 16826400), NYU’s cancer study began in 2009 (NCT00957359), and Imperial College London (April 2019) and Johns Hopkins (September 2019) opened dedicated research centers. Johns Hopkins Center for Psychedelic and Consciousness Research
- 2020 onward
Voters in Oregon (2020) and Colorado (2022) approved supervised, licensed psilocybin services, and New Mexico passed a medical program in 2025. Our legal page has the details.
How it’s thought to work
What researchers propose, and how much is still unknown.
A key that fits one lock best. The body converts psilocybin into psilocin, which acts mainly on the brain’s serotonin 2A receptors (Dinis-Oliveira, 2017). In a 1998 study, a drug that blocks that receptor also blocked psilocybin’s effects in healthy volunteers (Vollenweider et al.).
Quieter hubs, looser networks. Brain-imaging studies in healthy volunteers found reduced activity and coupling in hub regions of the “default mode network”, which is busy when the mind wanders (Carhart-Harris et al., 2012). A 2024 study found the biggest changes in that same network, some lasting weeks (Siegel et al.).
New connections, so far mostly in the lab. Psilocin encouraged nerve cells to grow new branches in a dish (Ly et al., 2018), and a single dose increased connection points in mice for about a month (Shao et al., 2021).
What isn’t known: the imaging studies are small and short, the growth findings come from cells and animals, and no one has shown that these brain changes cause any benefit in people.
Common questions about the research.
Research questions
Has psilocybin been approved as a medicine?
Not as of November 7, 2026. The FDA has given psilocybin programs Breakthrough Therapy designations, which speed up review but aren’t approvals. One company has said it expects to finish its application soon, and approval would still need the FDA’s decision and a change in federal scheduling.
Do these trial results apply to microdosing?
No. The trials on this page gave one to three large doses in supervised sessions with psychological support. Blinded microdosing studies so far haven’t beaten placebo on their main outcomes.
Who first isolated psilocybin?
The Swiss chemist Albert Hofmann at Sandoz, in 1958, working with the French mycologist Roger Heim on Psilocybe mexicana, a Mexican mushroom Heim had grown in culture. Hofmann reported its structure and synthesis the same year.
How does psilocybin work in the body?
The body converts psilocybin into psilocin, which acts mainly on serotonin 2A receptors. Researchers are studying how it changes communication between brain networks and how it may affect the growth of connections between nerve cells.
Our products haven’t been studied or evaluated for any condition, and nothing here is medical advice.
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