Cat's claw is an herb popular among the indigenous people of Peru, where it is used to treat cancer, diabetes, ulcers, arthritis, and infections, as well as to assist in recovery from childbirth. It is also used as a contraceptive. There are two primary species of cat’s claw used medicinally: Uncaria tomentosa and Uncaria guianensis .
A 4-week, double-blind, placebo-controlled trial evaluated the potential benefits of cat’s claw ( Uncaria guianensis species) for the treatment of osteoarthritis . 3 A total of 45 individuals with osteoarthritis were enrolled. Of these, 30 were treated with cat’s claw extract, and 15 were given placebo. Individuals in the treatment group showed reduced pain with activity as compared to those in the placebo group. However, no comparative improvements were seen in knee pain at rest or at night, nor in knee circumference.
This pilot trial suggests that the Uncaria guianensis species of cat’s claw may be a useful treatment for osteoarthritis. Another study compared the effectiveness of a proprietary combination of cat’s claw with glucosamine sulfate, a widely used dietary supplement for osteoarthritis. Researchers reported the results as positive, but because there was no placebo group the overall effectiveness of this cat’s claw combination product cannot be determined. 6 More research will be necessary to verify this potential use of the herb.
In a double-blind, placebo-controlled trial of 40 individuals undergoing conventional treatment for rheumatoid arthritis , use of an extract made from Uncaria tomentosa modestly improved symptoms in individuals with rheumatoid arthritis, as compared to placebo. 5 The researchers conducting this trial made use of recent information indicating that there are two different subtypes of Uncaria tomentosa , identifiable based on the chemicals found in them. For this trial, they used the form containing pentacyclic oxindole alkaloids, as opposed to tetracyclic oxindole alkaloids.
Numerous widely varying forms of cat’s claw are available commercially. The optimum dosage of each type is not known. In addition, the precise differences in action between the two species of cat’s claw, Uncaria tomentosa and Uncaria guianensis , as well as the pentacyclic and tetracyclic forms of Uncaria tomentosa (see above) are not known.
In general, use of cat’s claw has not been associated with adverse effects more serious than occasional digestive upset or allergic reactions. However, full safety studies have not been completed, and there has been one report of kidney failure apparently triggered by cat's claw. 4
Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.
Some evidence suggests that cat's claw might interact with various medications by affecting their metabolism in the liver, but the extent of this effect has not been fully determined. 2
3. Piscoya J, Rodriguez Z, Bustamante SA, et al. Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis . Inflamm Res. 2001;50:442-448.
5. Mur E, Hartig F, Eibl G, et al. Randomized double blind trial of an extract from the pentacyclic alkaloid-chemotype of uncaria tomentosa for the treatment of rheumatoid arthritis. J Rheumatol . 2002;29:678-681.
6. Mehta K, Gala J, Bhasale S, et al. Comparison of glucosamine sulfate and a polyherbal supplement for the relief of osteoarthritis of the knee: a randomized controlled trial [ISRCTN25438351]. BMC Complement Altern Med. 2007 Oct 31. [Epub ahead of print]
Last reviewed December 2015 by EBSCO CAM Review Board
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