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Cat’s Claw

Cat’s claw, or uña de gato as it is also called, has piqued many people’s interest lately, first because it comes from remote and exotic rain forests, and second, because it is believed to act on the immune system.

Both species referred to as cat’s claw are climbing woody vines (lianas) in the Amazon forest. The name refers to the small sharp spines on the stem near the leaf, curved back like a cat’s claw.

U. guianensis has been used by native people in South America to treat intestinal problems and to heal wounds.

The bark is used by different tribes for different purposes: Some find it an effective contraceptive, and others use it to treat gonorrhea.

This plant is widely used to relieve the pain of rheumatism and to reduce inflammation, as well as for dysentery and ulcers. This species of cat’s claw is preferred in the European market.

U. tomentosa, from the Peruvian headwaters of the Amazon, is often used for arthritis, ulcers, and other intestinal problems.

In addition, it is prized as a general tonic for its “life-giving” properties and is used for certain skin diseases.

The North American marketplace provides the major commercial outlet for this species. The bark is the part of the plant generally used for medicinal purposes.

Active Ingredients

Research on the constituents of uña de gato was begun only a few decades ago. Both species appear to contain alkaloids. U. tomentosa also contains quinovic acid glycosides and some novel triterpenes.


Traditional use by Amazonian tribes includes the treatment of a number of digestive disorders. Uña de gato is sometimes promoted in the United States to treat problems such as hemorrhoids, gastritis, colitis, ulcers, diverticulitis, and leaky bowel.

These applications appear to be based more on reports of folk medicine from the Amazon than on clinical or animal studies.

In the test tube, most of the alkaloids of U. tomentosa can be shown to activate immune system cells.

Several quinovic acid glycosides are active against various viruses in the laboratory.

Many of these compounds also counteract inflammation caused experimentally in rat-paw tests.

An important alkaloid lowers blood pressure, relaxes and dilates peripheral blood vessels, slows heart rate, and lowers cholesterol. Another acts as a diuretic.

The immune-stimulating effects of U. tomentosa have attracted attention for the possibility that the herb might be useful against cancer or HIV.

Studies of its use in the context of medical treatment of these life-threatening conditions are needed.


Standard dose information is not available.

Special Precautions

Pregnant women should not take cat’s claw because its safety and mode of action have been inadequately studied.

In test tube studies, however, extracts of this herb have not caused mutations in cells; indeed, they appear to protect against mutations.

Adverse Effects

No serious reactions have been reported in the literature.

Possible Interactions

No interactions with other drugs or herbs have been reported in the literature.

Because of the limited information available, it seems prudent not to combine U. tomentosa with other herbs or drugs that affect the immune system such as cortisone-like drugs or cyclosporine.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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