Devil's claw is a perennial plant native to desert regions of southern Africa and Madagascar. The common name of the plant, which is actually a translation of the German Teufelskralle, is derived from the plant's unusual fruits, which are covered with thorny, claw-like barbs. The plant lies dormant most of the year, awakening during times of sporadic rainfall to bring forth lush green leaves and bright red, trumpet-shaped blossoms. In order to store enough moisture to survive in its desert habitat, devil's claw has developed a specialized root system consisting of primary roots, which are roughly 1 meter in length, and several secondary storage roots, or tubers, which resemble potatoes. These tubers are harvested in autumn and dried for health purposes.
Pharmacological experiments conducted on devil's claw extracts have shown analgesic and antiinflammatory activity. The constituents believed responsible are a group of compounds known as iridoid glycosides, one of which, harpagoside, is widely viewed to be the herb's main active component.
The daily dosage approved by Commission E is 4.5 grams of dried root or equivalent preparations. There are no known side effects at this dosage. Clinical trials have used extracts providing the equivalent of 6 grams of dried root per day with no apparent toxicity. Devil's claw is not recommended for people with gastric or duodenal ulcers.