Psychedelics can cause changes in perception, mood, consciousness, cognition, or behaviour, including a heightened sensory perception, altered perception of time and an increased inner awareness. They are distinguished from other classes of drugs by their capacity to reliably induce these states of altered perception, thought and feeling that are not experienced otherwise except in dreams or at times of religious exaltation. One way to describe them is as non-specific amplifiers of consciousness. These features, combined with psychotherapy, show promising results for a host of mental health issues, such as depression, (end-of-life) anxiety, addiction, and PTSD. 

Clinical research into psychedelics began in the 1950s but was shut down for mostly political reasons in the beginning of the 1970s. For more than a decade now, there has been a renewed interest in the therapeutical potential of psychedelics. In the United States, MDMA therapy for PTSD and psilocybin therapy for depression have both been granted “breakthrough therapy” status by the FDA. Psychedelic substances are known for having a great safety profile. In a ranking of personal and social harms caused by both legal and illegal drugs, psilocybin mushrooms, LSD and MDMA scored significantly better than legal substances such as alcohol, nicotine and benzodiazepines, or illegal ones such as cocaine and even cannabis.