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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.
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
1. Jones K. Cat's claw. Herbs for Health. 1996;Sept-Oct:42-46.
2. Budzinski JW, Foster BC, Vandenhoek S, et al. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine. 2000;7:273-282.
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.
4. Hilepo JN, Bellucci AG, Mossey RT. Acute renal failure caused by 'cat's claw' herbal remedy in a patient with systemic lupus erythematosus. Nephron. 1997;77:361.
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 Last Updated: 12/15/2015