Psychedelics are a class of drugs which are defined by their phenomenology, their distinct but varying psychological effects. Classic psychedelics include the serotonin 2a receptor agonists LSD (lysergic acid diethylamide), mescaline, psilocybin, and DMT (dimethyltryptamine). Atypical psychedelics include glutamate antagonists like ketamine and PCP (phencyclidine) as well as monoamine-releasing drugs like MDMA (3,4-methylenedioxymethamphetamine, colloquially known is its street variant “Ecstasy”).
The term psychedelics was coined by the psychiatrist Humphry Osmond in 1957 and is supposed to mean “mind-revealing” because the psychedelic experience may allow glimpses into the functioning of the cognitive system and, if you will, the unconscious. Put less metaphorically, psychedelics may alter sensory perception, cognitive functions, and sometimes even the sense of self. It should also be noted that they may have a variety of not yet fully understood undesirable side-effects.
Psychedelics were used in therapy and research from the 1950s to the 1970s in Europe and the U.S., when great hopes were placed in its therapeutic potential. These hopes never realized and the substances were placed under strict international control for a variety of reasons. At present, they fall under the UN Convention on Psychotropic Substances 1971 (with the exception of Ketamine) and their use is outlawed, even for most medical uses, in almost all countries. Since the 1990s, however, they have again become the object of scientific studies, especially in neuropsychopharmacology and experimental psychiatry. This has been termed the “psychedelic renaissance”.
Preliminary studies with psilocybin and MDMA indicate their potential for treating mental illnesses. Around the world, research examines their use in the treatment of depression, anxiety, addiction, and obsessive-compulsive disorders. If the promises of these substances materialize, it is likely that they will be approved for psychiatric use, presumably embedded in other psychotherapeutic treatments (called “psychedelic-assisted psychotherapy”). An new drug application for MDMA, in comination with a specific psychotherapy, was rejected by the U.S. FDA in 2024. The next attempt to bring a psychedelic to market is expected by the end of 2026.
