Extracts of the secondary tubers of Devil's Claw (Harpagophytum procumbens) are recommended for the supportive treatment of degenerative painful rheumatism. There was observed an improvement of motility and a reduction of pain sensation in several clinical studies. Pharmacological experiments have shown analgesic, antiphlogistic and antiinflammatory actions. Most important constituents are iridoid glycosides, which are supposed to contribute mainly to the observed effects. However, the entire extract has to be considered as active ingredient.