Real-world data from 2,363 participants in Oregon and Colorado shows effect sizes comparable to controlled clinical trials
Aurora, Colo., August 12, 2026 — Researchers at the University of Colorado School of Medicine have completed the first large retrospective analysis of real-world outcomes from regulated psilocybin services in Oregon and Colorado, drawing on data from 2,363 participants treated by 253 licensed facilitators between December 2024 and March 2026.
Psilocybin, in combination with psychological support, has shown promise in clinical trials for a broad spectrum of psychiatric disorders, including depression and anxiety. Adverse events are generally mild in clinical trials in which participants are carefully pre-screened. But how well these results generalize to real-world populations is uncertain and important for the public and policy makers around the world, where interest on such services is growing.
Key findings:
- 49% average reduction in depression scores (PHQ-9) two weeks after dosing
- 51% average reduction in anxiety scores (GAD-7) two weeks after dosing
- Effect sizes comparable to controlled clinical trials of synthetic psilocybin, at a similar average dose (29 mg)
- Benefits were apparent in people currently prescribed SSRI/SNRIs, suggesting patients may not need to discontinue their antidepressants before treatment
- Participants traveled from all 50 states, with the majority coming from outside their home state
Serious adverse events were rare: of 2,363 dosing sessions, only five involved a serious event, none clearly attributable to psilocybin, including two EMS calls (one suspected cardiac event, one later determined to be kidney stones) and one fall without injury. The most common adverse events overall were mild and transient, primarily nausea and anxiety during the dosing session. Among participants with baseline suicidal risk who had follow-up data available, most reported improvement, 22 of 28 reported a decreased frequency of suicidal ideation after dosing, and none reported worsening beyond their baseline level. Separately, among 103 participants who reported no suicidal ideation at baseline, 11 reported suicidal risk two weeks after dosing, a concerning finding that warrants stronger safety monitoring across regulated programs.
“This is the first real-world evidence that regulated psilocybin services can produce the kind of benefit we’ve seen in controlled trials, at meaningful scale,” said Scott Thompson, PhD, corresponding author and Professor in the Department of Psychiatry at CU Anschutz. “It also shows us where we need better data going forward to ensure that these services can be delivered safely.”
The data was collected through a digital platform built by Althea, a Boulder-based public benefit corporation that provides compliance and data infrastructure to facilitators and centers in both states.
“Psychedelics have real potential to change how people experience their lives, but that potential only matters if we understand how it plays out in the real world,” said Niko Skievaski, co-founder and CEO of Althea. “Studies like this one are what will shape sound policy and better care delivery as this field matures.”
Aggregated, de-identified outcomes from this ongoing collection are publicly available at be.withalthea.com/psilocybin-outcomes, which updates continuously and may reflect figures from a later period than the study’s fixed analysis window. The manuscript will be available on medRxiv while it is under peer-review at a medical journal.
About The Department of Psychiatry at the University of Colorado School of Medicine
The Department of Psychiatry is a wide-ranging community of staff and faculty dedicated to serving the mental health needs of people across Colorado, training leaders in psychiatry and mental health care, and conducting groundbreaking research to identify the causes of mental illness and substance use disorders and identify, develop, and implement innovative prevention and treatment strategies that enhance quality of life. Learn more at https://medschool.cuanschutz.edu/psychiatry.
About Althea:
Althea is a Boulder-based public benefit corporation that provides compliance, payments, and data infrastructure for regulated psychedelic care programs. Learn more at withalthea.com.
