Origin story
Dhanvantari is the physician of the gods and an avatar of Vishnu, and the tradition of Ayurveda honours him as its divine source. During the churning of the Ocean of Milk he rose from the waters holding the pot of amrita, the nectar of immortality, and the gods and asuras paused their struggle at the sight.
He is depicted with four hands bearing the conch, the discus, healing herbs and the pot of amrita, sometimes with a leech as a sign of the physician's craft. Dhanteras, the eve of Deepavali, is his day, and the Thottuva Dhanwanthari Temple in Ernakulam district is one of Kerala's best-known shrines where he is worshipped for health and healing.
Source: Wikipedia: Dhanvantari — https://en.wikipedia.org/wiki/Dhanvantari