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

Cat's claw (Uncaria spp)

Abstract and key points

  • Cat’s claw is a woody vine indigenous to the Amazon rainforest and other tropical areas of South and Central America.
  • Cat’s claw is said to treat a range of disorders, including cancer.
  • The current evidence from preclinical data suggesting anticancer activity is not confirmed by clinical trials. Two clinical trials investigating the role of cat’s claw in alleviating the adverse effects of chemotherapy are not conclusive.
  • Adverse effects are mostly gastrointestinal problems associated with high doses. Interactions with immunosuppressants and anticoagulants might theoretically occur.

Cat's claw or ‘Uña de Gato’ is a thick woody vine classified in the Rubiaceae family. For medicinal purposes, the stem bark or root from the species Uncaria tomentosa and U. guianensis are most commonly used. These have traditionally been used for allergies, asthma, wound healing, viral infections, fevers, arthritis, gastric ulcers, rheumatism, inflammation, contraception and menstrual irregularities.

Uncaria tomentosa and U. guianensis contain over 60 different biologically active compounds that could be complementary and/or synergic in their actions. Despite some positive preclinical data, there are no clinical trials investigating cat’s claw as a direct anticancer agent. There is not enough evidence for other outcomes. Only two clinical trials investigated the role of cat’s claw in alleviating the adverse effects of chemotherapy. While in the first trial cat’s claw was not effective in reducing the most prevalent adverse effects, the second trial reported reduce neutropenia caused by chemotherapy. One small uncontrolled trial suggests improvement of quality of life and fatigue but no effects on biochemical and inflammatory markers or tumour response. 

Cat’s claw seems well tolerated at normal clinical doses but larger doses have been reported to cause some abdominal pain or gastrointestinal problems, including diarrhoea. Historically cat's claw has been used as an immunostimulant as well as for its antifertility effects. It can also reduce platelet aggregation and could theoretically be an anticoagulant.

Read about the regulation, supervision and reimbursement of herbal medicine at NAFKAMs website CAM Regulation.


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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