4-Acetoxy-N,N-dimethyltryptamine (also known as 4-AcO-DMT, 4-Acetoxy-DMT, O-Acetylpsilocin, and psilacetin) is a novel psychedelic substance of the tryptamine class. 4-AcO-DMT is chemically similar to psilocybin, the active ingredient in psilocybin mushrooms (magic mushrooms). It belongs to a group known as the substituted tryptamines which act by stimulating serotonin receptorsin the brain.
The synthesis of 4-AcO-DMT was first reported in 1963 by Albert Hofmann and Franz Troxler. However, its properties were not examined and no further studies were carried out. A 1999 paper by David E. Nichols suggested it as a useful alternative to psilocybin for pharmacological research. Reports of human use began to surface following its appearance on the online research chemical market in the 2010s.
User reports indicate that the subjective effects of 4-AcO- are near identical to those of psilocybin mushrooms. Like psilocybin, 4-AcO- is theorized to act as a prodrug to psilocin, which may account for this similarity. Characteristic effects include geometric visual hallucinations, time distortion, enhanced introspection, and ego loss. 4-AcO-DMT’s classical psychedelic effects and favorable tolerability profile has led it to become popular among novel psychoactive substance users, particularly those seeking mystical-like or entheogenic experiences.