Ayurveda or Ayurvedic medicine is a system of medicine with historical roots in the Indian subcontinent. Globalized and modernized practices derived from Ayurvedic traditions are a type of complementary or alternative medicine. In the Western world, Ayurveda therapies and practices (which are manyfold) have been integrated in general wellness applications and as well in some cases in medical use.
The main classical Ayurvedic treatises begin with legendary accounts of the transmission of medical knowledge from the gods to sages, and thence to human physicians. Thus, the Sushruta Samhita narrates how Dhanvantari, "greatest of the mighty celestials," incarnated himself as Divodasa, a mythical king of Varanasi, who then taught medicine to a group of wise physicians, including Sushruta himself. Ayurvedic therapies have varied and evolved over more than two millennia. Therapies are typically based on complex herbal compounds, while treatises written after about 1000 CE introduced mineral and metal substances (perhaps under the influence of early Indian alchemy or rasaśastra). Ancient Ayurvedic treatises also taught surgical techniques, including rhinoplasty, perineal lithotomy, the suturing of wounds, and the extraction of foreign objects.
Although laboratory experiments suggest it is possible that some substances in Ayurveda might be developed into effective treatments, there is no evidence that any are effective as currently proffered. Ayurvedic medicine is considered pseudoscientific. Other researchers consider it a protoscience or trans-science system instead. Close to 21% of Ayurvedic U.S. and Indian-manufactured patent medicines sold through the Internet were found to contain toxic levels of heavy metals, specifically lead, mercury, and arsenic. The public health implications of contaminated metals in India are unknown.
Some scholars assert that Ayurveda originated in prehistoric times, and that some of the concepts of Ayurveda have been discovered since the times of Indus Valley Civilization and earlier. Ayurveda significantly developed during the Vedic period and later some of the non-Vedic systems such as Buddhism and Jainism also developed medical concepts and practices that appear in the classical Ayurvedic treatises. Humoral balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness. Ayurveda names three elemental substances, the doshas (called Vata, Pitta and Kapha), and states that a balance of the doshas results in health, while imbalance results in disease. Ayurveda has eight canonical components, which are derived from classical Sanskrit literature. Some of the oldest known Ayurvedic texts include the Suśrutha Saṃhita and Charaka Saṃhita, which are written in Sanskrit. Ayurvedic practitioners had developed various medicinal preparations and surgical procedures by the medieval period. Today, according to a study by the University of Minnesota, about 90% of Indians use some form of Ayurvedic medicine.