A meta-analysis of six randomized, double-blind clinical trials involving 528 participants (about 51% female, median age 39.8 years) found that therapeutic single doses of psilocybin for depression and anxiety are associated with several acute adverse effects. Compared to placebo or low-dose psilocybin, psilocybin significantly increased the risk of headache (nearly double), nausea (nearly nine times), anxiety (more than double), dizziness (nearly six times), and elevated blood pressure (more than double). Psilocybin was not linked to paranoia or transient thought disorder. The adverse effects were tolerable and resolved within 48 hours, but the authors call for future studies to better manage these effects.
Current literature most strongly supports MDMA and intravenous ketamine as treatments for PTSD. Under professional supervision, these agents may reduce PTSD symptoms and are generally well tolerated. However, findings require cautious interpretation because of limitations including treatment expectancy effects and potential inadequate blinding. Additional randomized controlled trials of other psychedelics, such as psilocybin and lysergic acid diethylamide, are necessary to evaluate their effectiveness for PTSD.