4-AcO-DMT

4-AcO-DMT (4-acetoxy-N,N-dimethyltryptamine), also called psilacetin or O-acetylpsilocin, is a synthetic psychedelic of the tryptamine class. It was first made by Albert Hofmann and Franz Troxler in 1963 and was later proposed by chemist David Nichols in 1999 as a cheaper alternative to psilocybin for research. It subsequently appeared on the online research-chemical market and is sometimes nicknamed "synthetic mushrooms" because its effects closely resemble those of psilocybin mushrooms. It is usually taken orally as a powder or in capsules.

4-AcO-DMT is a prodrug of psilocin: after it is swallowed, the body's enzymes remove an acetate group to release psilocin (4-HO-DMT) — the very same active molecule that psilocybin is converted into when someone eats magic mushrooms. Psilocin is a serotonin receptor agonist whose psychedelic effects are driven mainly by activation of the 5-HT2A receptor, the same mechanism as psilocybin and the classic psychedelics. Because both psilocybin and 4-AcO-DMT converge on psilocin, their effects are expected to be closely comparable, though whether 4-AcO-DMT also has some activity of its own before conversion is not fully established.

Effects are widely reported to be very similar to psilocybin mushrooms: visual changes and enhancement, shifts in emotion and thought, introspection, and, at higher doses, ego dissolution and immersive psychedelic experiences. The experience typically lasts around 4 to 6 hours, with an onset commonly reported as somewhat faster than mushrooms (around 20 to 40 minutes). Some users report less nausea and physical "body load" than with mushrooms, though this is based on user reports rather than controlled study.

Because 4-AcO-DMT becomes psilocin in the body, its risk profile broadly mirrors that of psilocybin: challenging or frightening experiences ("bad trips"), anxiety, disorientation, and the potential to destabilize people with a personal or family history of psychosis. Rapid tolerance develops with repeated use, with cross-tolerance to psilocybin and LSD. Two cautions are specific to it being an unregulated synthetic: because it is sold as a powder on the research-chemical market, purity and dose accuracy vary and mislabeling is possible, so a given quantity may be stronger or weaker than expected; and because it has never been formally studied in humans in controlled trials, its long-term effects are less well characterized than psilocybin's. Like other serotonergic psychedelics, combining it with MAO inhibitors or other serotonergic drugs is a concern.