Study of Oregon's legal psilocybin program finds gains and rare serious harms

A study of people who used Oregon's legal psilocybin program is mostly reassuring, with some warning signs. Researchers led by Oregon Health and Science University (OHSU) followed about 346 adults who went to state-licensed psilocybin service centers. The results, published in JAMA Network Open on August 19, 2026 by Korthuis and colleagues, found that more than half reported improvement in mental health symptoms. Serious adverse reactions were rare.

What the study found

Most participants did better after their sessions. More than half reported that their symptoms improved, according to NPR's coverage of the study.

The safety findings are where readers should slow down:

• Four serious adverse reactions were reported, and all four happened in people using psilocybin for the first time.
• Three participants reported new thoughts of death or suicide one week after their session.
• By three months, the number of participants reporting new thoughts of death or suicide had doubled.

These are small numbers in a group of about 346 people, but they're a reminder that psilocybin isn't risk-free, even in a supervised, licensed setting. First-time users appear in every serious case, which is worth knowing for anyone considering a first session. For more on risks and warning signs, see our psilocybin safety guide.

Why the results need caveats

Outside experts cited in NPR's coverage pointed to two big limits. First, it was uncontrolled: there was no placebo or comparison group, so the study can't separate the effect of psilocybin from other factors, such as people's expectations. Second, the sample was affluent, so the results may not apply to people who can't afford a licensed session.

Controlled trials show why that first point matters. A German phase 2b trial in treatment-resistant depression, published in JAMA Psychiatry in May 2026, did not meet its primary goal: 17.0% of people given 25 mg of psilocybin responded at week 6, compared with 10.6% on placebo, a gap that wasn't statistically significant. A 2025 analysis of 17 trials in JAMA Network Open found that control groups in psilocybin trials improved far less than control groups in SSRI or esketamine trials, and its authors said psilocybin's efficacy "might" be overestimated.

What a licensed session in Oregon involves

Oregon's program, created by voters through Measure 109 in 2020, lets adults 21 and older take psilocybin at a licensed service center with a licensed facilitator. The first center was licensed on May 5, 2023. Outside that system, possessing psilocybin is a misdemeanor in Oregon, and it remains a Schedule I drug under federal law.

A separate study adds context on what clients actually get. Researchers at Washington University School of Medicine in St. Louis posed as prospective clients and reached 15 of Oregon's 22 active centers. All of them followed state safety screening rules, and none allowed clients to take psilocybin home. The median session cost was $1,900, and no center took insurance, which is consistent with the OHSU study's affluent sample.

For how to find a licensed center and what to expect, see our guide to Oregon psilocybin service centers.