95% of Oregon Psilocybin Study Participants Saw Improvements in Depression, PTSD
By Ashleigh Hollowell | August 19, 2026
Image by Michael M from Pixabay | CC0
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Adverse effects were found to be "uncommon" among a cohort of nearly 350 adults who participated in the first-ever U.S. state-regulated psilocybin study in Oregon. Not all participants sought psilocybin for mental health treatment, yet:
- 92.2% reported improvements in depression, anxiety, and overall mental wellbeing one month after receiving treatment.
Oregon became the first state to legalize psilocybin in 2020, paving the way for therapeutic research and development within a regulated framework.
Since its legalization, establishing clinical safety guidelines has been crucial given Oregon’s recreational model for psilocybin, distinct from the medical approach seen with cannabis.
"Just because something isn’t a medical model doesn’t mean you can’t have mental health benefits," said Dr. Todd Korthuis, lead author of the study and professor of medicine at Oregon Health and Science University. "Still, people [with] serious mental health or medical conditions should talk with their healthcare providers before seeking services."
During the Oregon Health and Science University-led study:
- Participants received a psilocybin dose in a controlled environment facilitated by a trained professional overseeing safety protocols.
- They reported depression and anxiety symptoms using standardized scales (PHQ-9 and GAD-7) and shared information about overall mental wellbeing, life satisfaction, harms, and service satisfaction.
At three months:
- 90.2% of patients still reported beneficial experiences.
- Only 4 (1.2%) experienced adverse behavioral reactions requiring medical attention.
- 7 (2.3%) reported their experience as "harmful" after three months.
- 95% reported a decrease in moderate-to-severe depression, anxiety, PTSD, and an increase in overall mental wellness and life satisfaction.
- Almost 60% ranked the experience among the top 10 most meaningful of their lives.
Physical health:
- Zero participants reported a serious event or adverse impact on their physical health overall.
"Safety was very similar to what we’ve seen with psychedelics in clinical settings," said Korthuis. "That’s important because there was a big question around whether safety in carefully controlled psilocybin clinical trials would translate into real-world use."