The following is a list of psychedelic drugs of various chemical classes, including both naturally occurring and synthetic compounds. Serotonergic psychedelics are usually considered the "classical" psychedelics, whereas the other classes are often seen as having only secondary psychedelic properties; nonetheless all of the compounds listed here are considered psychoactive and hallucinogenic in humans to some degree. Some of these compounds may be classified differently or under more than one category due to a unique structural classification, multiple mechanisms of action, or the fact that the precise pharmacodynamic actions of the compound are not yet completely understood. Because of the vast amount of possible substitutions and chemical analogs of most psychedelic compounds, the total diversity of chemical compounds which produce psychedelic effects in humans is not fully reflected within this list, leaving room for many that have not yet been sufficiently investigated and others that have not yet been discovered. Naturally occurring compounds are marked with a †. Serotonergic psychedelics (serotonin 5-HT2A receptor agonists) Indoles Tryptamines (more specifically alkylated tryptamines]) Psilocin†, also known as '4-HO-DMT'; another active constituent of the Psilocybe genus of mushrooms; also a metabolite of psilocybin and psilacetin Psilocybin†, also known as '4-PO-DMT'; the primary active constituent of the Psilocybe genus of mushrooms; its effects are partially attributed to psilocin, to which it is a prodrug via dephosphorylation Bufotenin†, also known as '5-HO-DMT' and dimethylserotonin; another constituent of the skin and venom of psychoactive toads, its psychedelic activity is disputed; also a metabolite of 5-MeO-DMT Baeocystin†, also known as '4-PO-NMT'; another active constituent of the Psilocybe genus of mushrooms; its psychedelic activity is disputed Aeruginascin†, also known as '4-PO-N-TMT', an active constituent of the mushroom Inocybe aeruginascens 5-MeO-DMT†, the primary active constituent of the skin and venom of psychoactive toads, a prodrug to bufotenin via demethylation N,N-Dimethyltryptamine†, also known as 'DMT'; the primary active constituent of the Amerindian brew ayahuasca; endogenously present in various plants and animals, including humans, possibly a trace amine neurotransmitter 5-Bromo-DMT†, was found in the marine invertebrates Smenospongia aurea and Smenospongia echina, as well as in Verongula rigida N-Methyl-N-ethyltryptamine, also known as 'MET' N-Methyl-N-isopropyltryptamine, also known as 'MiPT' N-Methyl-N-propyltryptamine, also known as 'MPT' N,N-Diethyltryptamine, also known as 'DET' N-Ethyl-N-isopropyltryptamine, also known as 'EiPT' N-Methyl-N-butyltryptamine, also known as 'MBT' N-Propyl-N-isopropyltryptamine, also known as 'PiPT' N,N-Dipropyltryptamine, also known as 'DPT' N,N-Diisopropyltryptamine, also known as 'DiPT' N,N-Diallyltryptamine, also known as 'DALT' N,N-Dibutyltryptamine, also known as 'DBT'