Sennosides are hydroxyanthracene glycosides derived from Senna leaves. They have been used as natural, safe time-tested laxatives in traditional as well as modern systems of medicine. Sennosides (Senna) is a medication used to treat constipation and empty the large intestine before surgery. The medication is taken by mouth or via the rectum. It typically begins working in minutes when given by rectum and within twelve hours when given by mouth. It is a weaker laxative than bisacodyl or castor oil. Senna is an FDA-approved nonprescription drug for adults and children ages 2 years and older. It is also used for bowel preparation before colonoscopy and diagnostic imaging.