In addition to their mind-altering effects, psychoactive plants were also valued for their ability to heal, reduce pain, fatigue or hunger. Numerous species with psychoactive properties were and are still used medicinally, such as the opium poppy (Papaver somniferum L.) or hemp (Cannabis sativa L.), two of the oldest and most widely-used psychoactive plants in Asia and Europe. These plants affect the central nervous system in different ways to produce altered states of consciousness. It is important to note that a small variation in the dose of many of these plants determines whether it is defined as a medicine, as a psychoactive substance or as a poison, since these plants contain highly toxic alkaloids that can be fatal to humans.
In addition to psychoactive plants, some societies also use animals (including several species of fish, frogs and toads) and fungi for religious, spiritual, magical and medicinal purposes. Examples of fungi with hallucinogenic properties are Claviceps purpurea, several species of the genus Amanita and Psilocybe (the so-called “magic mushrooms”), used since prehistoric times and depicted in a prehistoric cave in Spain. In the American continent, indigenous groups have used plants with hallucinogenic properties for centuries. Examples are coca (Erythroxylum coca Lam.), tobacco (Nicotiana tabacum L.), cacti such as peyote (Lophophora williamsii (Lem. ex Salm-Dyck) J.M. Coult.) from México, and san pedro from the Andes (Trichocereus macrogonus (Salm-Dyck) Riccob.).
In Europe, many psychoactive plants belong to the Solanaceae family, such as mandrake (Mandragora officinarum L.), henbane (Hyoscyamus niger L.) or deadly nightshade (Atropa belladonna L.). Highly toxic due to the presence of alkaloids such as scopolamine, atropine or hyoscyamine, these plants were, and still are, used in modern medicine to treat a variety of conditions.
Known since antiquity, psychoactive plants played an important role during the Middle Ages when witches, sorcerers and wizards made use of them to prepare their various perfumes, ointments, fumigations, potions and concoctions. Such practices were prosecuted by the Spanish Inquisition and many witches were imprisoned, tortured and burnt at the stake.
Psychoactive plants were also used as love philtres and fertility boosters. They helped to foresee the future, to bring good luck, to heal and to cause pain to, or even kill enemies. They were important ingredients of witches’ ointments, the so-called ‘unguentum pharelis’ or ‘unguentum populi’, which caused hallucinations and a flying sensation when ingested. To produce the desired effects, plants were taken orally, inhaled or rubbed onto the skin.
Solanaceae were not the only plants used for magic rituals in mediaeval Europe. Others included black hellebore (Helleborus niger L.), aconite (Aconitum napellus L.), foxglove (Digitalis purpurea L.) or hemlock (Conium maculatum L.).
In recent decades, the ingestion of psychoactive substances has had a huge impact on human society. This ingestion, mainly associated with recreational use, should not overshadow the importance of the traditional and historical use of such plants. Their historical impact in the field of medicine, by healing and alleviating or suppressing the pain of millions of people, is significant.