Dose Optimization of MDMA-Assisted Therapy for PTSD

This study is testing different doses of MDMA-assisted therapy — a treatment that combines a controlled dose of MDMA (sometimes known as "ecstasy") with structured psychotherapy sessions — to find the most effective and safest dose for treating PTSD (post-traumatic stress disorder) in military veterans. **You may be eligible if...** - You are a U.S. military veteran aged 18 or older - You have a current diagnosis of PTSD - You are able to swallow pills - You agree to have study sessions recorded - You can provide a contact person who can be reached in case of emergency - If you can become pregnant, you agree to use contraception and test negative for pregnancy before each treatment session **You may NOT be eligible if...** - You have a medical condition that makes taking a stimulant-type drug dangerous (e.g., uncontrolled high blood pressure, heart conditions) - You have significant psychiatric or medical history that poses a safety concern - You have symptomatic liver disease - You have a history of dangerously low sodium or abnormal body temperature - You weigh less than 48 kg (approximately 106 lbs) - You currently abuse drugs or alcohol - You have recently received electroconvulsive therapy (ECT) or ketamine therapy Talk to your doctor to see if this trial is right for you.