https://en.wikipedia.org/wiki/Mitragyna_speciosa
Traditional use
In cultures where the plant grows, it has been used in traditional medicine. The leaves are chewed to relieve musculoskeletal pain and increase energy, appetite, and sexual desire in ways similar to khat and coca.[9] The leaves or extracts from them are used to heal wounds and as a local anesthetic. Extracts and leaves have been used to treat coughs, diarrhea, and intestinal infections.[3][4][19] Kratom is often used by workers in laborious or monotonous professions to stave off exhaustion as well as a mood enhancer and/or painkiller.[19] In Thailand, kratom was "used as a snack to receive guests and was part of the ritual worship of ancestors and gods."[21] The herb is very bitter and is generally combined with a sweetener.[20]