Abstract Chapter 16 of Addiction Medicine covers hallucinogens, dissociative drugs, and empathogens. Hallucinogens, also termed psychedelics, are a large and diverse group of substances, some of which occur in fungi and plants and some which are chemically synthesized. Some have psychostimulant properties as well. They include psilocybin, mescaline, dimethyltryptamine (DMT), ayahuasca, lysergic...