Harpagophytum
Harpagophytum procumbens, also called grapple plant, wood spider and most commonly Devil's Claw, is a plant of the sesame family, native to South Africa. It got its name from the peculiar appearance of its hooked fruit. The plant's large tuberous roots are used medicinally to reduce pain and fever, and to stimulate digestion. European colonists brought Devil's Claw home where it was used to treat arthritis.
H. procumbens are mainly found in the eastern and south eastern parts of Namibia, Southern Botswana and the Kalahari region of the Northern Cape, South Africa. H. Zeyheri is found in the northern parts of Namibia (Ovamboland) and southern Angola. The active ingredient is harpagoside with values ranging in both species from 1.0% to 3.3%.
The name "devil's claw" is also used for several species of North American plants in the genus Proboscidea, as well as urtica dioica.

# Medicinal Uses
The two active ingredients in Devil's Claw are Harpagoside and Beta sitosterol. It is claimed that these possess anti-inflammatory properties. The British Herbal Pharmacopoeia recognises Devil's Claw as having analgesic, sedative and diuretic properties.  Most studies involve chronic use rather than acute treatment of pain.
Devil's Claw is also claimed to be beneficial for treating diseases of the liver, kidneys, gallbladder and bladder, arthritis and rheumatism. It is said to help alleviate problems with and improve the vitality of the joints, as well as stimulating appetite and aid digestion, increase cholesterol and fatty acids in the blood. Devil's Claw has been recommended for treating diabetes, hardening of the arteries, lumbago, gastrointestinal disturbances, menstrual difficulties, neuralgia, headache, heartburn and gout.
Several studies have been performed using Doloteffin, a standardized preparation of Devil's Claw. A series of small-scale studies completed in Germany found that H. procumbens was indistinguishable from Vioxx in the treatment of chronic low back pain, and was well-tolerated after more than four years of treatment of H. procumbens alone. H. procumbens also seems efficacious in the treatment of arthritis-caused hip and knee pain.  An author involved in several studies on Devil's Claw and pain relief had the general conclusion that a minimum 50 mg per dose standardized extract was an alternative to synthetic analgesics with a low risk of adverse events.  A separate 2006 systematic review of herbal medications for low back pain reached the conclusion that a standardized daily dose between 50 and 100 mg of harpagoside performed better than a placebo, and an unspecified dose of harpagoside demonstrated relative equivalence to 12.5 mg per day of Vioxx.
Devil's claw can also be used externally to treat sores, ulcers, boils and skin lesions.

# Adverse reactions
Devil's claw may interfere with the action of Ticlopidine and Warfarin, and patients should consult with a physician before combining Devil's claw with these medications.  In addition, Devil's Claw promotes the secretion of stomach acid, leading to difficulties in those with peptic ulcers, gastritis or excess stomach acid.  Care should also be taken for individuals with gallstones.

# Notes
-  Applied health article on Devil's Claw
-  Due to the natural variability of herbal extracts, the results of studies using different products and preparations are difficult to compare
-  Article comparing Vioxx and Doloteffin
-  Follow-up study of patients taking Doloteffin alone
-  German article on H. procumbens and hip/knee arthritis pain
-  German article discussing Devil's Claw extract for pain relief
-  Herbal medicine for low back pain (article from NIH)
-  Kroger article on Devil's Claw drug interactions
-  Kroger article on Devil's Claw