Rhamnus is a genus of about 110 accepted species of shrubs and small trees, commonly known as buckthorns, in the plant family Rhamnaceae. Cascara sagrada comes from the bark of the small tree Rhamnus purshiana. Cascara is native from northern California to British Columbia and east to the Rocky Mountains in Montana. It is often found along stream sides in the forests in valleys and in moist montane forests.
Cascara sagrada is a stimulant laxative and used for the relief of constipation and haemorrhoids and as a rectoanal postoperative treatment. It works by causing muscle contractions in the intestines, helping move stool through bowels. As with any laxative, you should use it when you have stomach pain, nausea, or vomiting. If you have any chronic intestinal issues, do not use Cascara. Any women who are pregnant or breastfeeding should not use cascara either.