Psychedelic therapy refers to therapeutic practices involving the use of psychedelic drugs, particularly serotonergic psychedelics (e.g. LSD, psilocin and DMT). As an alternative to synonyms such as "hallucinogen", "entheogen", "psychotomimetic" and other functionally constructed names, the use of the term psychedelic ("mind-manifesting") emphasizes that those who use these drugs as part of a therapeutic practice believe these drugs can facilitate beneficial exploration of the psyche. Proponents of psychedelic therapy also believe psychedelics enhance or unlock key psychoanalytic abilities, and so make it easier for conventional psychotherapy to take place.
Psychedelic therapy in the broadest possible sense of the term is likely as old as humanity's ancient knowledge of hallucinogenic plants itself. Though usually viewed as predominantly spiritual in nature, elements of psychotherapeutic practice can be recognized in the entheogenic or shamanic rituals of many cultures.
The use of psychedelic agents in Western therapy began in the 1950s, after the widespread distribution of LSD to researchers by its manufacturer, Sandoz Laboratories. Research into experimental, chemotherapeutic and psychotherapeutic uses of psychedelic drugs was conducted in several countries over the next 10-15 years. In addition to the release of dozens of books and creation of six international conferences, more than 1000 peer-reviewed clinical papers detailing the use of psychedelic compounds (administered to approximately 40,000 patients) had been made available by the mid 1960’s.  Proponents believed that the use of psychedelic drugs facilitated psychoanalytic processes, and that their studies showed that it was particularly useful for patients with problems that were otherwise difficult to treat, including alcoholics, although the trials did not meet the methodological standards required today.
Alcoholics who underwent LSD treatment often reported acute transformations in their personalities and lifestyles, with early studies reporting a 50% success rate after a single high dose session. Unfortunately, the studies that reported such a high percentage of alcoholics were successfully treated (and continued to remain sober a year or two later) had insufficient controls, lacked objective measures of genuine change, and failed to conduct rigorous follow-up interviews with subjects. Although the most ardent followers of psychedelic treatment for alcoholism and drug addiction have failed to produce legitimate results in this area, it would be naïve to claim that a psychedelic experience actually has little to no effect on alcoholics. Bill Wilson, the founder of Alcoholics Anonymous, reported that his experience with LSD closely resembled the religious transformation that led him to overcome the compulsion to drink.  The fact is that even the most powerful and intense experience—drug-induced or not—cannot provide absolute assurance that one will not revert back into habitual addictive tendencies.
Many researchers initially believed that low-dose LSD sessions could be helpful in treating depression, as one of the direct effects of the substance seemed to be a euphoric, heightened emotional state in the user. However, studies along these lines were discontinued after it was realized that LSD had no truly consistent pharmacological effects on depression itself. Taking the often profound and life-changing effects of the LSD experience from a different angle, other researchers were convinced that such treatment could successfully substitute for the electroshocks and insulin coma therapy whose goals were to significantly alter the fundamental personality structure or subjective value-system of the patient. According to Stanislov Grof, “The major obstacle to their systematic utilization for therapeutic purposes was the fact that they tended to occur in an elemental fashion, without a recognizable pattern, and frequently to the surprise of both the patient and the therapist. Since the variables determining such reactions were not understood, therapeutic transformations of this kind were not readily replicable." (*) However, the attempts to further systematize and objectively interpret these experiences in a controlled, non-arbitrary, predictable way finally resulted in the development of psychedelic therapy. 
Efforts to utilize the purely pharmacological properties of LSD and other drugs in psychedelic treatment were completely abandoned after it was realized that they had no direct chemotherapeutic curative properties. Rather, it is through the unique introspective state attained by the patient (with the drug as a ‘catalyst’), in combination with a positive, empathetic relationship with an experienced psychotherapist, that the actual ‘healing’ can occur.
Many proponents of psychedelic therapy believe that the treatment can be of great use to those suffering from terminal illnesses who experience severe depression, pain, and fear that comes with the feeling of impending death. In 1965, research consisting of providing a psychedelic experience for the dying was conducted at the Spring Grove State Hospital in Maryland. Of 17 dying patients who received LSD after appropriate therapeutic preparation, one-third improved "dramatically," one-third improved "moderately," and one-third were unchanged by the criteria of reduced tension, depression, pain, and fear of death. 
Ibogaine has been tried as a treatment for drug addicts although this is not sanctioned by the FDA, and has to be conducted abroad, due to possible health risks. Another study showed that psychopaths had the possibility of gaining more from an LSD therapy session than non-psychopaths. Studies on alcoholics and psychopaths using LSD were carried out by Humphrey Osmond, a controversial researcher.
In the mid-1960s, in response to concerns regarding the proliferation of the unauthorized use of psychedelic drugs by the general public (especially the counterculture), various steps were taken to curtail their use. Bowing to governmental pressure, Sandoz halted production of LSD in 1965, and in many countries LSD was banned, or made available on a very limited basis that made research difficult. Gradually, more and more restrictions were placed on medical and psychiatric research conducted with LSD and other psychedelic substances. In a congressional hearing in 1966, Senator Robert Kennedy questioned the shift of opinion with regards to this potentially rewarding form of treatment, noting that, "Perhaps to some extent we have lost sight of the fact that (LSD) can be very, very helpful in our society if used properly" (Subcommittee on Executive Reorganization, 1966 p. 63).
In 1968 the American Journal of Psychiatry published an article that detailed the way in which various forces had successfully discredited legitimate LSD research (Dahlberg, 1968). The essay describes how powerful parties in government and the pharmaceutical industry were able to influence the inclusion of such research in the medical community by canceling any ongoing experimentations and analysis in addition to labeling genuine scientists as charlatans who were responsible for the degeneration of well-founded science and psychiatric treatment. 
By 1970, LSD and many other psychedelics were permanently placed into the most-restrictive "Schedule I" category by the Drug Enforcement Administration, along with widely-used illicit drugs like heroin. Schedule I compounds are claimed to possess "significant potential for abuse and dependence" and have "no recognized medicinal value," effectively rendering them illegal for any purpose. This highly politicized legislation directly disregarded the findings of hundreds of scientific and medical articles documenting the value of psychedelics as beneficial aids to psychotherapy and therapeutics for a number of psychological disorders. Despite these objections from the scientific community, authorized research into therapeutic applications of psychedelic drugs had been discontinued worldwide by the 1980s.
Research and therapeutic sessions have nevertheless continued to be performed, in one way or another, to the present day. Some therapists have exploited windows of opportunity preceding scheduling of particular substances (e.g. MDMA, Salvia divinorum), or developed extensive non-drug techniques for achieving similar states of consciousness (e.g. Holotropic Breathwork). For the most part, however, since the early 1970s psychedelic therapy has been conducted by an underground network of people willing to conduct what they consider to be therapy sessions using illegal substances. In the event that any board-certified therapist were found to be doing this, they risk losing their careers as well as their freedom. However in many countries, anyone is entitled to call themselves a therapist. A handful of qualified scientific researchers, especially since the late 1990s, have succeeded in obtaining limited legal permission for research studies and human trials of psychedelics as treatments in cases of severe, refractory psychiatric disorders.
The effects of psychedelic drugs on the human mind are complex, varied and difficult to characterize, and as a result many different "flavors" of psychedelic psychotherapy have been developed by individual practitioners. Some aspects of published accounts of methodologies are discussed below.
Psycholytic therapy involves the use of low to medium doses of psychedelic drugs, repeatedly at intervals of 1-2 weeks. The therapist is present during the peak of the experience and at other times as required, to assist the patient in processing material that arises and to offer support when necessary. This general form of therapy was utilized mainly to treat patients with neurotic and psychosomatic disorders. (1) The name, coined by Ronald A. Sandison, literally meaning "soul-dissolving", refers to the belief that the therapy can dissolve conflicts in the mind. Psycholytic therapy is historically the predominant approach to psychedelic psychotherapy in Europe.
An advantage of psychedelic drugs in exploring the unconscious is that a conscious sliver of the adult ego usually remains alert during the experience. Throughout the session, patients remain intellectually alert and remember their experiences vividly. In this highly introspective state, they also are actively cognizant of ego defenses such as projection, denial, and displacement as they react to themselves and their choices in the act of creating them. (1) The ultimate goal of the therapy is to provide a safe, mutually compassionate context through which the profound and intense reliving of memories can be filtered through the principles of genuine psychotherapy. Aided by the deeply introspective state attained by the patient, the therapist assists him/her in developing a new life framework or personal philosophy that recognizes individual responsibility for change.
Psychedelic therapy involves the use of very high doses of psychedelic drugs, with the aim of promoting transcendental, ecstatic, religious or mystical peak experiences. This approach differs strongly from the dialog-based processing of psychodynamic material upon which many other methodologies are based. As such, it is more closely aligned to transpersonal psychology than to traditional psychoanalysis. Psychedelic therapy is primarily practiced in North America.
In Czechoslovakia, Stanislav Grof, a world-renowned expert on psychedelic therapy, developed a form of treatment that appeared to bridge both of these main forms. He systematically analyzed the suppressed mental content uncovered by the LSD experience in a Freudian or Jungian psychoanalytic context in addition to giving significant value to the overarching transpersonal, mystical, or spiritual experience that often allowed the patient to re-evaluate their entire life philosophy. 
The Chilean therapist Claudio Naranjo helped develop a branch of psychedelic therapy which utilized drugs like MDA, MDMA, Harmoline, and Ibogaine—substances that do not involve the same degree of perceptual and emotional alteration as LSD. 
Anaclitic Therapy. The term anaclitic (from the Greek anaklinein—to lean upon) refers to primitive, infantile needs and tendencies directed toward a pre-genital love object. Developed by two London psychoanalysts, Joyce Martin and Pauline McCririck, this form of treatment is similar to psycholytic approaches as it is largely based on a psychoanalytic interpretation of abreactions produced by the treatment, but it tends to focus on those experiences in which the patient re-encounters carnal feelings of emotional deprivation and frustration stemming from the infantile needs of their early childhood. Accordingly, the treatment was developed with the aim to directly fulfill or satisfy those repressed, agonizing cravings for love, physical contact, and other instinctual needs re-lived by the patient. Accordingly, the therapist is completely engaged with the subject, as opposed to the traditional detached attitude of the psychoanalyst. With the intense emotional episodes that came with the psychedelic experience, Martin and McCririck aimed to sit in as the ‘mother’ role who would enter into close physical contact with the patients by rocking them, giving them milk from a bottle, etc. (Grof)
Hypnodelic Therapy. Hypnodelic Therapy, as the name suggests, was developed with the goal to maximize the power of hypnotic suggestion by combining it with the psychedelic experience. After training the patient to respond to hypnosis, LSD would be administered, and during the onset phase of the drug the patient would be placed into a state of trance. Levine and Ludwig found the combination of these techniques to more effective than the use of either of these two components separately. (Grof)
Developments from 1980 — present
Owing to the largely illegal nature of psychedelic therapy in this period, little information is available concerning the methods that have been used. Individuals who have published information on psychedelic psychotherapy in this period include Stanislav Grof (LSD Psychotherapy), Ann Shulgin (TiHKAL, with Alexander Shulgin), and Myron Stolaroff (The Secret Chief, about the underground therapy done by Leo Zeff) and Athanasios Kafkalides.
Current Research & Therapy
Current (legally tolerated) research into possible therapeutic value of psychedelics includes using psilocybin with terminally ill patients, with the intention of helping them come to terms with their condition, and for pain relief. A pilot study showed that Psilocybin could be safely given to those with OCD and showed trends for improvement of symptoms but the study did not clearly establish whether or not the patients were helped by the treatment. Other experimental uses under investigation include the use of MDMA, more commonly known as Ecstasy, to treat Posttraumatic stress disorder (PTSD) in people who did not benefit from available PTSD treatments. This has been questioned because of possible long-term health risks.
Despite the attempts to completely invalidate the legitimacy of the nature of psychedelic drug-assisted therapy, it appears as if a recent revitalization of clinical trials involving such substances has been gradually emerging. A handful of dedicated proponents, like Rick Doblin, the founder of the Multidisciplinary Association for Psychedelic Studies, continue to lobby the FDA and other agencies to permit full-scale research on the benefits of psychedelic drugs. 
Dr. John Halpern, Associate Director of substance abuse research at Harvard University’s McLean Hospital, is leading a new resurgence of psychedelic medical treatments. He recently gained approval from the Food and Drug Administration to administer MDMA (commonly known as ecstasy) to late-stage cancer patients, and has been working to receive a research grant for LSD experimentation in patients suffering from intense migraines. "There are medicines here that have been overlooked, that are fundamentally valuable," says Halpern. Halpern and other colleagues at Harvard are currently attempting to convince government officials that LSD, as well as psilocybin (the active component in psychotropic mushrooms), should be used in clinical trials for those suffering from these extremely painful “cluster headaches.” 
- "Shamanic Guidelines for Psychedelic Medicine" by Michael Winkelman, IN Winkelman, Michael, and Roberts, Thomas B. (editors) (2007) Psychedelic Medicine: New Evidence for Hallucinogens as Treatments 2 Vols. Westport, CT: Praeger/Greenwood.
- Stanislav Grof, LSD Psychotherapy, 1980. (3rd edn. MAPS, ISBN 0-9660019-4-X )
- Stanislav Grof, LSD Psychotherapy, 1980. (3rd edn. MAPS, ISBN 0-9660019-4-X )
- Stanislav Grof, LSD Psychotherapy, 1980. (3rd edn. MAPS, ISBN 0-9660019-4-X )
- Myron Stolaroff, The Secret Chief: Conversations with a pioneer of the underground psychedelic therapy movement, Multidisciplinary Association for Psychedelic Studies (MAPS) 1997. ISBN 0-9660019-0-7 (hardcover) ISBN 0-9660019-1-5 (paperback)
- Moreno FA, Wiegand CB, Taitano EK, Delgado PL (2006) "Safety, tolerability, and efficacy of psilocybin in 9 patients with obsessive-compulsive disorder" J Clin Psychiatry. 67(11):1735-40.
- Psychedelics, dissociatives and deliriants
- Transpersonal psychology
- Stanislav Grof
- Peter Baumann (Psychiatrist) (Founder of the SÄPT, Swiss doctor's society for psychedelic therapy)
- Samuel Widmer
- Humphry Osmond
- Multidisciplinary Association for Psychedelic Studies (MAPS)
- 3,4-Methylenedioxyamphetamine, aka MDA
- Methylenedioxymethamphetamine, aka MDMA
- Lysergicaciddiethylamide, aka LSD
- 4-Phosphoryloxy-N,N-dimethyl-tryptamine, aka Psilocybin
- History of LSD Therapy (Ch. 1 of Grof's, LSD Psychotherapy)
- Multidisciplinary Association for Psychedelic Studies (MAPS) includes books and research to read online.
- Athanasios Kafkalides, psychedelic therapist and researcher : biography, information and writings.
- , Research papers and articles on the role of psychoactive substances in psychological and shamanic healing practices.
- Turn On, Tune In, Drop Out … Get Well? Article about psychedelic therapy research in LitmusZine.