Psilocybin Therapy Shows Large PTSD Symptom Drop in Veterans Pilot Study

Veterans with severe, treatment-resistant PTSD experienced a large and statistically significant drop in symptoms after psilocybin-assisted therapy, according to a pilot trial published in Communications Medicine.

Clinician-rated PTSD scores fell by an average of 27.5 points from baseline to one-month follow-up — an effect size (d = 2.30) that dwarfs what existing PTSD medications typically deliver. Critically for a population at elevated risk, the trial detected no increase in suicidal ideation or behavior.

A small study with a big signal

This was an open-label pilot, meaning participants and clinicians knew what treatment was given, and there was no placebo group. Results this strong in a small, unblinded sample need confirmation in randomized trials — but they mirror a separate 2025 open-label trial in which a single 25 mg dose of psilocybin with psychological support produced rapid PTSD symptom reductions sustained through 12 weeks, with a manageable safety profile.

Why veterans are a focus

PTSD affects a disproportionate share of veterans, and existing treatments leave many without relief. The VA has begun running its own psychedelic studies, and Congress has directed funding toward psychedelic research for veteran mental health — a rare area of bipartisan agreement.

Larger randomized trials are now the priority. If the effect holds up, psilocybin-assisted therapy could become one of the most consequential additions to PTSD care in decades.