An extract made from the dried leaflets on the pods of Cassia angustifolia or Cassia acutifolia with cathartic activity. Dimeric glycosides in dried senna extract are converted to the active monoanthrones by bacterial action in the colon.

Senna is used on a short-term basis to treat constipation. It also is used to empty the bowels before surgery and certain medical procedures. Senna is in a class of medications called stimulant laxatives. It works by increasing activity of the intestines to cause a bowel movement.