Hallucinogens are chemicals that are capable of producing hallucinations, or altered states of perception. Hallucinogens are both naturally-occurring and artificial in nature. They include material from plantsand mushrooms (mescaline and psilocybin) as well as artificial compounds such as LSD, PCP, and MDMA.

Of the naturally-occurring hallucinogens, some are plant alkaloids such as hyosine (sometimes called scopolamine). Hyosine is a tropine alkaloid which can be found in Atropa belladonna (deadly nightshade) and Datura stramonium (Thorn apple, Jimsonweed). The symptoms of hyosine usage include dryness of the mouth and throat, dilated pupils, uncoordination, nausea, delirium, coma, and may cause death. Ingestion of this material has been carried out in the form of tea.

Historically, the alkaloids have been used for medicinal purposes. They mimic various nerve transmitters such as acetylcholine and serotonin. Certain fungi has also been used among native peoples of North and South America for their hallucinogenic properties...