Cascara sagrada is the dried, aged bark of a small tree in the buckthorn family native to the Pacific Northwest. The bark is harvested mostly from wild trees in Oregon, Washington, and southern British Columbia. The bark is aged for a year so that the active principles become milder, as freshly dried bark produces too strong a laxative for safe use; it also contains a compound that induces vomiting.
The name cascara sagrada is Spanish for "sacred bark". Long used as a laxative by Native American groups of the northwest Pacific coast, cascara sagrada bark was not introduced into formal medical practice in the United States until 1877. In 1890, it replaced the berries of the European buckthorn (R. catharticus) as an official laxative. It is still used in over-the-counter laxatives available in every pharmacy in the United States.
Dried, aged cascara sagrada bark is widely accepted as a mild and effective treatment for chronic constipation. The bark contains compounds called anthraquinones (cascarosides A and B) which are transformed by intestinal bacteria into substances that increase peristalsis in the large intestine and help restore its tone.
Cascara sagrada is available in capsules, extracts, and as dried bark. It is a little silly, however, to make a tea of the extremely bitter bark when you can go to a pharmacy for a fluid extract, or to a health food store for capsules, both of which are much easier to take.
Only the aged bark should be used. If you have chronic constipation, see your doctor for other approaches to avoid laxative dependency.