A randomized, double-blind, placebo-controlled single-ascending-dose study to identify a non-hallucinogenic dose of psilocybin in healthy adults.
medRxiv July 19, 2026 Naama Levy‐Cooperman, Edward M. Sellers, Paul Glue et al.
Low doses of psilocybin (0.5 to 4.0 mg) produce perceptible pharmacological effects without causing hallucinations, cognitive impairment, or increased anxiety. In a Phase 1 randomized, double-blind, placebo-controlled trial, 56 healthy adults received a single oral dose of psilocybin or placebo. No serious adverse events occurred; side effects were comparable to placebo, mainly somnolence. Psilocin appeared rapidly in the blood with dose-proportional exposure and a short half-life. Subjective drug effects were dose-related and distinguishable from placebo at or below 2.5 mg, but hallucination and altered-states scores remained low and not different from placebo.