homeopathy (hōmēŏpˈəthē) [key], system of medicine whose fundamental principle is the law of similars—that like is cured by like. It was first given practical application by Samuel Hahnemann of Leipzig, Germany, in the early 19th cent. and was designated homeopathy to distinguish it from the established school of medicine which he called allopathy. The American Institute of Homeopathy was founded in 1844, and the practice of homeopathy was popularized in the United States by the physician and senator Royal S. Copeland (1868–1938). It had been observed that quinine given to a healthy person causes the same symptoms that malaria does in a person suffering from that disease; therefore quinine became the preferred treatment in malaria. When a drug was found to produce the same symptoms as did a certain disease, it was then used in very small doses in the treatment of that disease. U.S. medical schools do not presently emphasize the homeopathic approach, although it has become popular among some physicians in European and Asian nations and is widely used by the public in over-the-counter medications.
See N. Robins, Copeland's Cure: Homeopathy and the War between Conventional and Alternative Medicine (2005).