Iatrochemistry (or chemical medicine) is a branch of both chemistry and medicine. ἰατρός (iatrós) was the Greek word for "physician" or "medicine". Having its roots in alchemy, iatrochemistry seeks to provide chemical solutions to diseases and medical ailments.
This area of science has fallen out of use in Europe since the rise of modern establishment medicine. However, iatrochemistry was popular between 1525 and 1660, especially in Flanders. Its most notable leader was Paracelsus, an important Swiss alchemist of the 16th century. Iatrochemists believed that physical health was dependent on a specific balance of bodily fluids. Iatrochemical therapies and concepts are still in wide use in South Asia, East Asia and amongst their diasporic communities worldwide.
The preparation of medicines had become a part of alchemy by the early modern period. Around 1350, John of Rupescissa advocated the extraction of the "essence" of both plants and minerals. He often used two relatively new substances during this period: an alcohol distilled from wine and strong mineral acids. Later, the author "Pseudo-Lull" (i.e. Ramon Llull or one of his followers) picked up and helped in expanding John of Rupescissa's theory.
The most impactive vocal proponent of iatrochemistry was Theopharastus von Honhenheim, also known as Paracelsus (1493–1541). He put his effort into the transmutation of metals and emphasized iatrochemistry in his works. Paracelsus believed that diseases were caused by poisons, but the poisons were not entirely negative. He suggested that poisons, or diseases, can also be cured by poisons. Thus, poisons could have beneficial medical effects. Paracelsus's claim led to many chemically prepared medicines in this period containing toxic components: arsenic, antimony, mercury, lead, and other heavy metals. However, his views were not accepted by many scholars until his incoherent writings were organized into more systematic form by his followers. Gradually, many physicians accepted Paracelsian remedies although some disagreed with Paracelsus's philosophy. Later, the physicians introduced chemical medicine in form of iatrochemistry, a system of medical explanation and practice.