Extensive research during the last 50 years has led to a clear understanding off Senna’s actions. The sennosides irritate the lining of the large intestine, causing muscles to contract strongly, resulting in a bowel movement about 10 hours after the dose is taken
Senna has always been specifically used for constipation. It is particularly appropriate when soft stool is required, for example in cases of anal fissures. Senna is a good short-term laxative but should not be taking in large amounts over a long period of time as that can lead to weakening the large bowel muscles. Short term is great.