In brief
- A team from the Oregon Health & Science University (OHSU) tracked 346 people who utilized the state’s legal psilocybin centers over a three-month period.
- Moderate to severe depression symptoms dropped from 42.2% to 16.5%; anxiety from 45.1% to 13.2%; and post-traumatic stress from 48% to 16.8%.
- Four individuals (1.2%) experienced serious adverse reactions; all were psychedelic-naive and had underlying mental health conditions. One required hospitalization.
Since 2023, Oregon has allowed legal access to psilocybin outside of clinical trials, provided in centers with trained facilitators and without the need for a medical diagnosis or prescription. Until now, rigorous scientific follow-up on the outcomes for those using this system was lacking. That has changed: a study from OHSU published August 19 in JAMA Network Open, which the authors describe as the largest analysis of psychedelics conducted outside of a controlled clinical trial setting.
Participants and Methodology
The team, led by P. Todd Korthuis, recruited 346 adults from 24 of the state’s 26 licensed centers between November 2024 and March 2026. The average age was 49.5 years, 52.5% were women, and the average psilocybin dose was 31.9 mg. Some 44.2% had never tried a psychedelic before. Participants completed validated questionnaires for depression (PHQ-9), anxiety (HADS), and post-traumatic stress (PCL-6) before their session and again at one week, one month, and three months. Retention was high, with 90.2% of participants still responding at the end of the follow-up period.
What the Data Shows
Improvements were evident by the one-month mark and were sustained, with a slight uptick, at three months. The proportion of participants with moderate or severe depressive symptoms fell from an initial 42.2% to 10.6% at one month and 16.5% at three months. Anxiety dropped from 45.1% to 11.9%, then to 13.2%. Post-traumatic stress decreased from 48% to 19.4% and then to 16.8%. Measures of mental well-being and life satisfaction also improved.
The safety section warrants careful reading, as it is where this work contributes the most. There were four serious adverse reactions (1.2% of the sample), all occurring in people without prior psychedelic experience who had underlying psychiatric conditions: one involved violent behavior that resulted in hospitalization, and the others included persistent anxiety, depression, and suicidal ideation throughout the follow-up. At one month, 10% reported persistent visual perceptions similar to HPPD, and 8.7% at three months, although only one person described them as truly bothersome.
Implications
This is an observational study without a comparison group or random assignment, meaning it cannot confirm that psilocybin alone caused these improvements. Selection bias may play a role, as participants chose to pay out-of-pocket for a session and then respond to questionnaires for months. Furthermore, the sample was predominantly white (86.7%) and highly educated, representing about 5% of those who have used the Oregon system, making it risky to generalize to other profiles. The authors themselves state this plainly.
Even so, the underlying data is solid: a model of supervised legal access, without medical filtering, has been operating for years, and for the first time, we have a prospective snapshot of its results and its pitfalls. It aligns with what we saw in the analysis of 2,363 cases in Oregon and Colorado, including the signal regarding suicidal ideation in vulnerable individuals that both studies urge us to monitor. Those who wish to place this in context can review our Psychedelics Guide and our harm reduction guidelines, which are particularly relevant for those arriving without prior experience or support.
Source
- Korthuis PT, et al. Safety and Mental Health Outcomes of Oregon State-Regulated Psilocybin Services. JAMA Network Open, August 19, 2026.
Educational content written from a harm reduction perspective and with respect for individual freedom. It is not a substitute for advice from a healthcare professional and is not intended to encourage or condemn any drug use.
