Yu Sang (; 1643âÂÂ1723), alternatively Ryu Sang (), courtesy name Yà Âjin (æ±ÂçÂÂ, ì¬ì§Â), was a royal court physician and politician of the Korean Joseon dynasty. He was a smallpox specialist who successfully treated three Joseon kings.
In 1693, due to having cured Sukjong's smallpox, he was granted a political office. Later he became the governor of Seosan, Goyang, Hapcheon and Saknyeong.
His experiences with smallpox are detailed in his book, Kogà Âm Kyà Ânghà Âm Hwalyubang ().
Supernatural anecdotes featuring him and a divine being circulated due to his fame.
He was a 23rd-generation descendant of the Munhwa Yu clan. His father Yu Kyà Ângjip () served as an observation officer (è§Âå¯Â使, gwanchalsa). His son Yu Chungnim () was also a medical practitioner who also wrote the agricultural text Chà Ângbo sallim kyà Ângje.