Senna, cascara sagrada, cape aloes, etc. are all herbal laxatives that are in a class that work by creating irritation to the intestinal lining resulting in the rapid expulsion of the contents of the intestines. In as little as a week of regular use this can result in a weakening of the bowel muscle which disrupts normal peristalsis and can lead to laxative dependence. There are OTC and prescription laxatives that work in this same manner. Other types of laxatives such as magnesium preparations, salt flushes, etc. work by using a different mechanism...but can have their own complications when used frequently. Avoid the regular use of laxatives and address the underlying causes of constipation.