Hallucinogens constitute a heterogeneous class of psychotropic substances under international control, belonging to a wide variety of chemical and pharmacological groups, and including such drugs as LSD, peyote, psilocybin, and more recently phencyclidine (PCP). Their use causes profound mental changes such as euphoria, anxiety, sensory distortion, vivid visual and auditory hallucinations, changes in behaviour, delusions, paranoid reactions, depression and a sense of identity loss. Principal problems created by the use and abuse of hallucinogens are very different from those posed by the abuse of depressants and stimulants. The known hallucinogens are not medicines. Since there is no lawful consumption of hallucinogenic substances, except for scientific experiments, no distinction can be made between their use and abuse; for the present, their consumption is considered an abuse. Because the production of, trade in and consumption of hallucinogens are, in the vast majority of cases, illegal, both the quantities produced and the number of consumers are unknown.
Among the large number of substances used at present, the main one is certainly LSD. It is an abbreviation of the German expression for lysergic acid diethylamide. LSD is a synthetic or more precisely a semi-synthetic compound, since it is not found in any natural substance; but lysergic acid, the raw material required for its production, is a natural product found in ergot of rye (Secale cornutum). For a psychedelic trip, 100-250 microgrammes of LSD is used in the form of a diluted solution or in a capsule. Drops of the solution are usually taken on a lump of sugar. Some people use STP (DOM, 2.5-dimethoxy-4-methylamphetamine) , or a mixture of LSD and STP. The letters 'STP' (Serenity, Tranquillity, Peace) designate a synthetic compound produced exclusively in underground laboratories.
Other hallucinogens, the abuse of which is widespread, are derivatives of tryptamine, in particular dimethyltryptamine (DMT) and diethyltryptamine (DET), but other substances are also used. In addition to these 'classic' substances, 'new' toxic substances are also often taken; such experiments frequently end in hospitalization.
The absorption of substances in order to produce hallucinations, visions and depersonalization constitutes a very different phenomenon from the abuse of narcotics. The feeling of well-being produced by a narcotic such as opium does not include fantasies, illusions or hallucinations. The idea of these phenomena comes from literary sources, and in the imagination of the general public they occupy a place which has no connection with reality. The effect of a narcotic like opium, although it is sometimes used in groups, is a solitary experience which cannot be shared with others; the feeling of well-being so induced is devoid of any social or sexual content. During a psychedelic trip, on the contrary, the feeling of being at one with the universe and in communication with others by extra-sensory means requires the presence of other people. The use of hallucinogenic substances is therefore usually part of a group activity.
During the 1960s, the myth that hallucinogenic substances could perfect the personality and broaden consciousness was strengthened by members of such groups at a time when young people ready for new experiences were faced with numerous material and cultural challenges of society. Drugs such as heroin were considered too dangerous to experiment with because of the possibility of addiction and the risk of incurring serious legal penalties. The new substances did not cause physical dependence, and their use was not (then) illegal; the danger of using them was therefore considered to be moderate. In this context, it should be noted that at the basis of this new wave of drug addiction, there are metaphysical elements which only occur sporadically in the history of the use and abuse of opiates, and that there is a certain undeniable similarity between the use of the new hallucinogens and that of 'ritual' drugs.
Many people are attracted only by the hallucinogenic effects of the psychedelic experience, which above all consist of unusual hallucinations that are difficult to describe. Hallucinogens may promote reactions of panic anxiety, fury, alteration in sense of time, touch, memory, identity, reality, lack of concentration and, as an after effect, paranoia or general insanity. The repeated abuse of hallucinogens is generally the 'wilful choice' of the user, rather than deriving from compulsion induced by the drug. Tolerance builds up rapidly and disappears rapidly, but chronic habitual overdose is very difficult if not impossible to treat. Physical reactions such as vomiting are frequent. The use of hallucinogens continues in tribal societies (particularly in Central and South America) for religious and spiritual purposes. Unstable and unpredictable drugs (e.g. LSD) have been connected with subsequent homicide, suicide and psychosis.
The complex reaction produced by LSD (in particular the phenomenon of depersonalization) changes the mental image of the body, and a feeling of detachment and of unreality are not limited to the duration of a 'trip'; on the contrary, the reappearance of these reactions several weeks or months after the 'trip' indicates the lasting effect of LSD on the central nervous system. The study of the connection between these reactions and the paranoid state of many people in hospital may reveal the price to be paid for experimenting with mental equilibrium.
Hallucinogen abuse is limited compared to most other drug types. There are about 2,008,000 abusers, a global rate of 0.47 per 1,000, but most of these are from the USA. In 1980, only 15 countries reported statistical data on hallucinogen abusers, although another 32 countries gave verbal reports of at least some abusers. Until 1976, the numbers generally reported were much larger, but since that time there appears to have been a marked decrease in the number of abusers worldwide. Only 2 countries have in recent years reported extensive abuse: the USA with 1,990,000 (9.1 per 1,000) and the Cayman Islands in the Caribbean with 35 abusers (3.2 per 1,000). Only 3 countries are in the moderate abuse range: Australia (0.7 per 1,000), Canada (0.14 per 1,000) and Switzerland (0.1 per 1,000).
These trends suggest that the international proselytizing by hallucinogen users in the 1960s may have been a time-limited phenomenon. The number of medical treatments after the use of hallucinogens is increasing. In 1967, a review of work on harmful reactions to LSD was published containing summaries of twenty detailed reports in which 221 adverse reactions are described, including 19 attempted suicides, 11 suicides, 4 attempted murders and 1 murder. Since this review, the number of medical reports has increased. However the number of fatal cases and the number of people treated do not indicate either the frequency or the danger of the use of LSD, since the 'trip' does not always end in hospitalization. Nonetheless, it should also be emphasized that, according to the reports on these reactions, it is impossible to guarantee a safe dosage, or a 'safe' personality that might not react in an unfavourable manner to LSD; a bad 'trip' is always possible, even in the case of an experienced 'traveller'.
Chronic effects of LSD have begun to be noted. Chronic states have been observed in those who use high doses of LSD (from 250 to 750 microgrammes per day) both frequently and regularly. According to some reports, the treatment of these persons is extremely difficult if not impossible.