Anthraquinone derivatives such as senna are stimulant laxatives.
Stimulant laxatives work by irritating the sensory nerve endings of the intestines, thus stimulating movement of the colon and reducing water absorption from the colon.
Constipation is generally described as a symptom of less than three bowel movements per week.
Although constipation is a very common symptom, some people suffer from chronic constipation that can interfere with their ability to perform daily tasks.
Chronic constipation may also cause people to strain excessively to defecate