PTSD Research: MDMA and Other Substances

Quick answer

Two large phase 3 trials found that MDMA-assisted therapy lowered PTSD scores more than placebo with therapy. In August 2024, however, the US FDA declined to approve it at that time, citing the reliability of safety data, no proof the benefit lasts beyond 18 weeks, and possible selection and expectation bias. Psilocybin for PTSD has only been tested in small, uncontrolled studies in the sources read. This page describes research, not treatment advice. If you are in crisis in the US, call or text 988, or call 911.

Evidence labels: approved medicine (none found for these uses), promising but limited, mixed, insufficient evidence. MDMA is a separate category from classic psychedelics such as psilocybin; see entactogens and why MDMA is not a classic psychedelic and the MDMA guide.

MDMA-assisted therapy: the trials

A 2026 living meta-analysis pooled six randomized trials (286 people), all sponsored by the same organization (MAPS). It found MDMA-assisted therapy lowered PTSD symptoms more than control short term, but rated overall certainty low and noted that expectancy, functional unblinding, study conduct and safety are not fully captured by standard bias tools. [3]

Label: promising but limited, and not approved.

The 2024 FDA response

The FDA's complete response letter (NDA 215455, August 2024) listed three main concerns. [4]

• Safety data reliability. The FDA said events relevant to abuse potential, including positive or euphoric effects, were not consistently collected, and inspections found unreported adverse events, leaving substantial concerns about the reliability of the safety data. [4]
• Durability. The effect was not shown to last beyond the 18-week end-of-study assessment. The long-term follow-up study had a single visit with timing from 6 months to 2 years, and many participants used other treatments in between. [4]
• Selection and expectation. About 40% of enrolled participants reported prior MDMA use, much higher than expected, which may point to selection bias and to functional unblinding, since people who know the drug are likelier to recognize it and expect benefit. [4]

The FDA suggested a new randomized double-blind trial with blinded long-term follow-up. [4] In July 2026 it also published final guidance for psychedelic drug trials, which discusses functional unblinding and states that the contribution of psychotherapy to the effect is not established. [5] We did not verify any development after the 2024 letter; check the FDA for current status. See also how to read a psychedelic clinical trial.

Other substances

• Psilocybin: The one study read was an open-label pilot of 12 US military veterans with treatment-resistant PTSD. It reported no serious adverse events and large symptom reductions. With no control group and 12 people, this is insufficient evidence of efficacy. [6]
• Other substances: Proper evidence not found in our searches of PubMed (2026-10-22) for randomized trials of other psychedelics for PTSD, other than the MDMA program above.

Safety and special groups

Trials excluded some groups and used trained staff and monitoring, so findings do not describe use outside clinics. NIDA notes poor mental health outcomes may be more likely outside clinical use. [7] Do not stop a prescribed medicine because of this page; speak with your prescriber.