FDA Clears Phase 2 Trial Testing Inhaled Cannabis for PTSD in Veterans
The U.S. Food and Drug Administration cleared a long-delayed Phase 2 clinical trial examining whether inhaled cannabis can reduce post-traumatic stress disorder symptoms in military veterans. Sponsored by the Multidisciplinary Association for Psychedelic Studies (MAPS) and funded through Michigan’s Veteran Marijuana Research Grant Program, the study is designed to test cannabis under conditions that resemble how many people use it outside a laboratory.
The study, known as MJP2, is a randomized, double-blind, placebo-controlled trial expected to enroll approximately 320 veterans with moderate to severe PTSD. Participants must have previously used cannabis or be considering its use. The trial will compare high-THC dried cannabis flower with placebo cannabis, with participants allowed to adjust their daily intake based on tolerability and symptom response.
That design is intended to address a central problem in cannabis research: many existing studies use low-potency products or tightly controlled doses that do not reflect real-world consumption. According to the public MJP2 protocol, the treatment period will last five weeks, followed by a one-week follow-up. The primary efficacy measure will be the change in PTSD severity, assessed with the Clinician-Administered PTSD Scale for DSM-5.
The FDA’s decision was regulatory clearance to conduct the study—not approval of cannabis as a treatment for PTSD. MAPS said the agency had placed the trial on partial clinical hold in 2021 and later issued five hold letters. The resulting negotiations focused on issues including the proposed THC concentration, smoking and vaping as delivery methods, and whether people without prior cannabis experience should be enrolled. MAPS submitted a formal dispute-resolution request in August 2024 before announcing that the FDA had cleared the study to proceed in November of that year.
The research builds on an earlier MAPS-sponsored pilot study involving 76 veterans. That trial reported symptom improvements during treatment, but its primary comparison between high-THC cannabis and placebo did not reach statistical significance on the main PTSD severity measure. The larger MJP2 study is intended to provide a more rigorous test while also collecting information about safety, sleep, pain, mood, medication use and problematic cannabis use.
PTSD can involve intrusive memories, avoidance, sleep disruption and persistent physical or emotional distress after trauma. Psychotherapy and medications remain the principal evidence-based treatments, but not every patient benefits from them or tolerates their side effects. At the same time, some veterans use cannabis to manage PTSD symptoms, creating a need for better evidence about both its potential benefits and its risks.
That evidence remains mixed. The U.S. Department of Veterans Affairs’ National Center for PTSD says current research does not establish cannabis as an effective PTSD treatment and notes that long-term use may be harmful for some people. The VA/Department of Defense clinical practice guideline recommends against using cannabis to treat PTSD. Those conclusions underscore why a placebo-controlled trial is important: personal reports of short-term relief cannot determine whether cannabis produces durable clinical improvement or whether benefits outweigh risks.
Michigan’s grant program uses revenue from the state’s legal cannabis market to support FDA-authorized research involving veterans. The state awarded MAPS approximately $12.9 million for MJP2, according to the Michigan Cannabis Regulatory Agency.
As of August 2026, MAPS lists MJP2 as being in the startup phase rather than as a completed or results-reporting trial. The organization has continued working on site agreements, study-drug logistics and regulatory requirements. No conclusions about the effectiveness of smoked or inhaled cannabis for PTSD can be drawn until the trial is completed and its results are independently evaluated.
