Overall, current evidence from clinical trials suggest that devil’s claw may be a useful treatment for arthritis; however, it is suggested, as with many herbal medicines, that evidence of effectiveness is not transferrable from product to product and that the evidence is more robust for products that contain at least 50 mg of harpagoside in the daily dosage.
An observational study of 6 months’ use of 3-9 g/day of an aqueous extract of devil’s claw root reported significant benefit in 42-85% of the 630 people suffering from various arthritic complaints. In a 12-week uncontrolled multicentre study of 75 patients with arthrosis of the hip or knee, a strong reduction in pain and the symptoms of osteoarthritis were observed in patients taking 2400 mg of devil’s claw extract daily, corresponding to 50 mg harpagoside. Similar results were reported in a 2-month observational study of 227 people with osteoarthritic knee and hip pain and non-specific low back pain and a double-blind study of 89 subjects with rheumatic complaints using powdered devil’s claw root (2 g/day) for 2 months, which also provided significant pain relief, whereas another double-blind study of 100 people reported benefit after 1 month. A case report suggests that devil’s claw relieved strong joint pain in a patient with Crohn’s disease.
Comparisons with standard treatment have also been investigated. In 2000, encouraging results of a randomised double-blind study comparing the effects of treatment with devil’s claw 2610 mg/day with diacerhein 100 mg/day were published. The study involved 122 people with osteoarthritis of the hip and/or knee and was conducted over 4 months. It found that both treatment groups showed similar considerable improvements in symptoms of osteoarthritis; however, those receiving devil’s claw required fewer rescue analgesics.
One double-blind, randomised, multicentre clinical study of 122 patients with osteoarthritis of the knee and hip found that treatment with Harpadol (6 capsules/day, each containing 435 mg of cryoground powder of Harpagophytum procumbens) given over 4 months was as effective as diacerhein (an analgesic) 100 mg/day. However, at the end of the study, patients taking Harpadol were using significantly fewer NSAIDs and had a significantly lower frequency of adverse events. In a 6-week study of only 13 subjects, similar benefits for devil’s claw and indomethacin were reported. A recent preliminary study comparing the proprietary extract Doloteffin with the COX-2 inhibitor, rofecoxib, reported a benefit with the herbal treatment but suggested that larger studies are still required. The herb is Commission E approved as supportive therapy for degenerative musculoskeletal disorders and ESCOP approved for painful osteoarthritis (ESCOP 2003).
Several double-blind studies have reported benefit with devil’s claw in people with back pain. A double-blind study of 117 people with back pain reported decreased pain and improved mobility after 8 weeks’ treatment with devil’s claw extract LI 174, known commercially as Rivoltan. Use of the same extract provided significant pain relief after 4 weeks in another randomised, double-blind placebo-controlled study of 63 subjects with muscle stiffness. Similar results were reported in two double-blind studies of 118 people and 197 people with chronic lower back pain.
Devil’s claw appears to compare favourably to conventional treatments. A 6-week double-blind study of 88 subjects comparing devil’s claw to rofecoxib found equal improvements in both groups. A follow-up of the subjects from that study who were all given devil’s claw for 1 year found that it was well tolerated and improvements were sustained. In an open, prospective study, an unspecific lower back pain treatment with Harpagophytum extract and conventional therapy were found to be equally effective.
Devil’s claw root is approved for relief of low back pain by ESCOP (ESCOP 2003).
Traditionally, devil’s claw has also been used to treat dyspepsia and to stimulate appetite. The bitter principles in the herb provide a theoretical basis for its use in these conditions, although controlled studies are not available to determine effectiveness. The herb is Commission E and ESCOP (2003) approved for dyspepsia and loss of appetite.
Traditionally, the herb is also used internally to treat febrile illnesses, allergic reactions and to induce sedation, and topically for wounds, ulcers, boils and pain relief, as well as for diabetes, hypertension, indigestion and anorexia.