Post-traumatic stress disorder is a huge problem for the American military. Numbers are hard to pin down, but the US Department of Veterans Affairs website says 10 to 20 percent of Iraq War veterans have PTSD in a given year. It’s difficult to treat for many reasons, but psychedelic drugs might offer some hope.

Earlier this month, researchers at the California-based Multidisciplinary Association for Psychedelic Studies (MAPS) published a report in the psychological journal The Lancet that suggests MDMA, or Ecstasy, is really good—staggeringly good—at treating PTSD when combined with therapy.

The researchers spent five years dosing 26 combat veterans and first responders with varying levels of MDMA in a clinical setting. The subjects were randomly assigned one of three doses—30 mg, 75 mg, and 125 mg—and treated to an eight-hour guided trip with a professional therapist. The results were impressive, the authors report.

“Although this was a small pilot study, the effect size was large and the results were significant,” Berra Yazar-Klosinski, MAPS Associate Director of Clinical Research and study co-author, told me in an email. “If these results are reproduced in Phase III trials, then the future is much brighter for treating PTSD.”

Before the study, many of the participants scored high on the Clinician Administered PTSD Scale (CAPS), a diagnostic tool that therapists and scientists use to measure the severity of PTSD symptoms in sufferers. “Fifty or greater is at least moderate symptom severity,” Yazar-Klosinski wrote. “However, on average participants had extreme PTSD symptom severity, which is above 80.” After, the mean CAPS score among study subjects fell from 87.1 to 38.8.

It’s important to stress that treating PTSD with drugs isn’t just about giving a patient ecstasy and walking away. “The setting is a comfortable living room furnished with armchairs for therapists and a futon for the participant,” Yazar-Klosinski told me. “There are typically fresh flowers brought in and light music. Participants wear eyeshades part of the time and alternate between periods of silence and discussion as the MDMA induces the therapeutic effects.”

The MDMA sessions are only part of the treatment package. Subjects took the drug three times, but the treatment was much more than a handful of trips. It all started with education. Before anyone took a drug, the therapists walked the patients and their families through the ins and outs of PTSD and how trauma affects the brain. “This helps the patients and their supporters to better articulate their needs and, together with the therapy team, set realistic goals,” Yazar-Klosinski said.

Overcoming PTSD is not necessarily about overcoming or releasing the traumatic past, but rather about making peace with it, according to Yazar-Klosinski. “Integration is an essential and ongoing process as the experience unfolds and resolves,” she wrote. “A nondirective approach to therapy based on empathetic rapport and empathetic presence is used to support the patient’s own unfolding experience and the body’s own healing process.”

That process involves follow up visits from therapists, phone calls, and continuing therapy. In many ways, Yazar-Klosinski told me, the MDMA supercharges traditional therapy. It’s not a magic bullet, but the research suggests it's a lubricant that makes psychotherapy much more powerful. “Three sessions with MDMA were sufficient for 68 percent of participants … to not satisfy PTSD criteria, 12 months after their last MDMA session,” Yazar-Klosinski said.

A 2016 meta-study of other PTSD therapies for veterans reported effectiveness rates well below those shown in the MAPS study that used MDMA in treatment. The results were so good compared to traditional therapy, in fact, that MAPS is pushing to designate MDMA treatment for PTSD as a breakthrough therapy with the US Food and Drug Administration. This would mean that the FDA could expedite the treatment through the regulatory process.

It’s important to note, again, that treating PTSD isn’t as simple as taking a hallucinogen and hoping for the best. In the MAPS study, trained professionals carefully worked with the vets and first responders to help them through their trauma. Even then, there were risks and adverse reactions and it might not be for everyone.

One participant with a pre-existing heart condition had an adverse reaction during one of the sessions. “The participant received several MDMA treatments with no issue. On the last MDMA treatment, the arrhythmia was exacerbated,” Yazar-Klosinski said. The participant went to the hospital, the symptoms abated, and the doctors couldn’t find anything wrong.

Nonetheless, this clinical trial is promising and illustrates the changing conversation around hallucinogenic drugs in society. More and more, scientists are taking them seriously and finding surprising therapeutic benefits in a good trip.