Understand the science and the policy

Start with what was actually tested. Every registered trial is on this register, with the ones that have reported results and the ones due to read out. For the published papers, search PubMed, the US National Library of Medicine’s index.

Three trials shaped the current debate, and each is worth reading in full rather than in headlines:

• Goodwin and colleagues, New England Journal of Medicine 2022, 387(18):1637-1648 (doi 10.1056/NEJMoa2206443). 233 people with treatment-resistant depression received a single 25 mg, 10 mg or 1 mg dose of psilocybin. At week 3 the 25 mg group differed from 1 mg by 6.6 points on the MADRS depression scale. Suicidal ideation and self-injury were reported more often in the 25 mg and 10 mg groups.
• Mitchell and colleagues, Nature Medicine 2021, a phase 3 trial of MDMA-assisted therapy for severe PTSD (doi 10.1038/s41591-021-01336-3).
• Mitchell and colleagues, Nature Medicine 2023, a second phase 3 trial in moderate to severe PTSD (doi 10.1038/s41591-023-02565-4).

The two MDMA trials above went to the FDA. On 4 June 2024 its Psychopharmacologic Drugs Advisory Committee voted 2 to 9 that the evidence showed effectiveness, and 1 to 10 that benefits outweighed risks. In August 2024 the FDA issued a complete response letter asking for another phase 3 trial (report).

Separately, the Institute for Clinical and Economic Review’s final report of 27 June 2024 concluded the evidence was not adequate to show a superior net health benefit over short-term trauma-focused psychotherapy, citing functional unblinding: participants could often tell whether they had received the drug.

The FDA’s own expectations for these trials are set out in Psychedelic Drugs: Considerations for Clinical Investigations, issued in draft on 26 June 2023 and in final form in July 2026 (docket FDA-2023-D-1987). The National Institute on Drug Abuse summarises the research on hallucinogens and on psilocybin.

• Johns Hopkins Center for Psychedelic and Consciousness Research
• Imperial College London Centre for Psychedelic Research
• NYU Langone Center for Psychedelic Medicine
• UC Berkeley Center for the Science of Psychedelics
• Usona Institute, a nonprofit medical research organisation
• Heffter Research Institute
• MAPS, an advocacy and research nonprofit

• RAND’s Drug Policy Research Center, Considering Alternatives to Psychedelic Drug Prohibition (2024): what use and supply look like today and the options open to federal and state policymakers.
• Oregon’s regulator, Oregon Psilocybin Services: how a licensed state program runs.
• Colorado’s Natural Medicine Division, which began accepting licence applications on 31 December 2024 and approved its first healing centre licence in April 2025.
• Psychedelic Alpha’s state law tracker, an industry analysis of bills and ballot measures.

For what the law is today, in general terms, see our legal status page.

These rules are not made out of view. The FDA accepts comments on any guidance at any time (21 CFR 10.115(g)(5)), including the psychedelic trials guidance, through docket FDA-2023-D-1987 on regulations.gov.

DEA scheduling proposals are published in the Federal Register with a comment period and the right to request a hearing. In 2022 the DEA proposed placing two research chemicals, DOI and DOC, in Schedule I. It received comments and hearing requests, withdrew the proposal in August 2022 and asked HHS for a new scientific evaluation, then proposed the scheduling again in December 2023.

Two more ways in: join a trial that is recruiting, which is how the evidence gets made, and tell us when this register gets something wrong.