Are hallucinogens clinically useful drugs?

 Potentially. Some hallucinogens have been studied for possible therapeutic benefits in treating mental disorders such as depression.  Ketamine was approved many years ago as an anesthetic for painful medical procedures. In March 2019, the medicine esketamine (called “Spravato” by the manufacturer) was approved by the Food and Drug Administration as a treatment for severe depression in patients that do not respond to other treatments. Esketamine is closely related to the drug ketamine which is used illicitly and so there are concerns about the potential for abuse of this newly approved medication. In response, esketamine will be limited to administration in medical facilities. Evidence has also mounted in recent years that psilocybin may be effective in treating depression, and this is currently being studied in clinical trials. Psilocybin is not approved by the Food and Drug Administration (FDA), but in 2018, the FDA granted “Breakthrough Therapy” designation to one pharmaceutical company to facilitate clinical trials for its psilocybin-assisted therapy for treatment-resistant depression; the trials will determine the most optimal dose of the drug. It has also been studied as a possible treatment for depression and anxiety suffered by people with terminal illnesses.