Written by Klara Rombauts, Italo M Cesari and the CAM-Cancer Consortium.
Updated March 9, 2017

Cat's claw (Uncaria spp)

What is it?


Cat's claw or “Uña de Gato” is a thick woody vine (liana) belonging to the Rubiaceae family 1,2.


The plant, described by its Spanish common name “Uña de Gato”, derives its name from hook-like thorns that grow along the vine 1. There are several species of cat’s claw but the two most common species used as a medicinal herb are U. tomentosa (Willd. DC.) and U. guianensis (Aubl, Gmel.). These species are indigenous to the Amazon rainforest and other tropical areas of South and Central America. Other common names include saventero, samento , vilcacora, etc. 1,2.


Fifty-six compounds have been isolated from U. tomentosa and an additional eight from U. guianensis based on a search in Reaxys (an online search and retrieval system for chemical compounds, bibliographic data, and chemical reactions) in December 2012. Among the 56 compounds isolated from U. tomentosa, pharmacological activity has been demonstrated for 27. Among the eight compounds isolated from U. guianensis pharmacological activity has been demonstrated for six 3-11. Characteristic phytochemicals belong to indole alkaloids (for instance, pentacyclic oxindoles such as pteropodine, isopteropodine, mytraphylline and tetracyclic oxindoles like rhyncophlline), triterpenes including quinovic acid and derivatives thereof, stigmasterol, sterols, flavonoids (procyanidins, catechins and flavonols, tannins), and low molecular weight carboxyl alkyl esters (CAEs).

Cat's claw is included in the United States Pharmacopeial Convention (USP) as a dietary supplement. In the pharmacopeia cat's claw consists of the inner bark of the stems of U. tomentosa (Willd.) DC. (Rubiaceae). It contains not less than 0.3% of pentacyclic oxindole alkaloids as isopteropodine, calculated on the dried basis, as the sum of speciophylline, uncarine F, mitraphylline, isomitraphylline, pteropodine and isopteropodine.

Application and dosage

In South America, about 20-30 g of the root or bark is prepared as a decoction in 1 litre of water for 20-30 minutes and the extract is consumed as tea. The dosage of a standard decoction for general health and maintenance is 0.5-1 cup of decoction once daily, up to three cups daily if necessary. Alcoholic extracts from the bark are also traditionally used 12,13.

Nowadays cat's claw is available in many different forms: dried cut-and-sifted root and stem, powdered root and stem, encapsulated powdered material or lyophilized aqueous extracts, tinctures, tablets and other types extracts. Cat’s claw is also available in preparations for external uses (ointments, gels).

History and providers

Cat’s claw has been used as a sacred plant of healing for over 2,000 years. The priests of the Asháninka Indian tribe in Central Peru considered cat's claw to have great powers and health-improving properties and used the herb to ward off disease. This tribe has the longest recorded history of use of this plant. They are also the largest commercial source of cat's claw from Peru today 13,14.

Alleged indications/claims of efficacy

Cat’s claw has been used traditionally as an anti-inflammatory, contraceptive, immunostimulant, cancer remedy and anti-viral 5.

Mechanism of action

The wide range of biological/pharmacological effects of Uncaria spp preparations are due to the concomitant presence of numerous and differently bioactive chemical structures that could be complementary and/or synergic in their actions 16. The pentacyclic oxindole alkaloids are immunostimulants and can be selectively cytostatic/cytotoxic to some cancer cells; they are considered biomarkers in alcoholic extracts of U. tomentosa; the tetracyclic oxindole alkaloids have effects on the cardiovascular system and DNA protection. Pentacyclic triterpenes are anti-microbial, anti-viral, and anti-inflammatory. Sterols appear to be anti-inflammatory only. Uncaria polyphenols (flavonoids) have strong antioxidant as well as antiviral, anti-allergic, anti-platelet, anti-inflammatory, and anti-tumour activities 13,16,17.

The suppressive effects of some aqueous U. tomentosa extracts on tumour cell growth would appear to be mediated by the induction of apoptosis 18,19. Moreover, U. tomentosa extracts are able to reduce the serum response of the proinflammatory cytokines TNF-α and IL-6, and to inhibit the nitric oxide production as well as the NF-κB activity 20-24. Dreifuss et al. 24, using an U. tomentosa hydroalcoholic extract in vivo, demonstrated that the anti-tumour activity could, at least partially, result from the ability of U. tomentosa to restore redox and metabolism homeostasis through downregulation of the NF-κB transcription factor and superoxide dismutase (SOD) activities.

Effects of cat’s claw have been shown in vitro in several cell lines of different tumour origins: breast 29,33, lung 28 and medullary thyroid carcinoma 38 as well as in glioma 32, neuroblastoma 32, melanoma 20,21, lymphoma and leukaemia cell lines 30. Although some results were confirmed in vivo in mice (metastatic melanoma 20,21 and Lewis lung carcinoma 28), more research is still needed in animal models and humans before any conclusions can be drawn 22,27,28,31.

Prevalence of use

There is no information available about the prevalence of use of cat’s claw worldwide but review papers describe it as one of the most popular herbs in the USA 13-15. In a survey on the use of herbal supplements amongst 998 black breast cancer survivors 0.9% reported using cat’s claw 37.

Legal issues

Cat's claw is not listed on the Food and Drug Administration’s Generally Regarded as Safe (GRAS) list 15. It is widely available on the internet and in pharmacies.


The product is available in several formulations and doses and the prices vary, which makes it impossible to predict the treatment cost. A one-month supply can range from €5 to €100.


Klara Rombauts, Italo M Cesari, CAM-Cancer Consortium. Cat's claw (Uncaria spp) [online document]. http://cam-cancer.org/The-Summaries/Herbal-products/Cat-s-claw-Uncaria-spp. March 9, 2017.

Document history

Revised in March 2017 by Barbara Wider.

Assessed as up to date in September 2014 by Barbara Wider.
Summary first published in February 2013, authored by Klara Rombauts and Italo M Cesari.


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