Cat's Claw (Uña de Gato)

What Is Cat's Claw?

Cat's claw is a vine that grows in Peru. The plant gets its name from pairs of large, curved thorns that grow along the vine. In Spanish, the vine's name is uña de gato. Its scientific name is Uncaria tomentosa. Traditionally, the inner bark and the root of the vine are used to make a tea. A similar vine, Uncaria guaianensis, lacks a potentially important compound. A Chinese variety, Uncaria rhynchophylla, has many similar compounds.

WARNING: A plant called "cat's claw" grows in northern Mexico and southern Texas. This plant, Acacia gregii_, has no known health benefits and its bark may be poisonous._

Natives of the Peruvian jungle, especially the Ashaninka tribe, have used cat's claw for hundreds of years as a medicine. It did not come to the attention of researchers until the 1970s.

Cat's claw contains chemicals called oxindole alkaloids. A researcher named Klaus Keplinger patented some of these based on evidence that they affect immune function. However, a patent is not the same thing as approval by the Food and Drug Administration. Keplinger has used cat's claw to treat some people with herpes or HIV.

Other research showed that cat's claw also contains different kinds of alkaloids that affect the central nervous system. These alkaloids might work against the alkaloids that affect the immune system. More research is needed.

What Are the Benefits of Cat's Claw?

Peruvian natives use cat's claw to treat inflammatory diseases like arthritis, to clean out the digestive tract and to treat cancer. It has also been used to treat dysentery, recovery from childbirth, and women's hormone imbalances.

In laboratory studies, cat's claw normalizes some immune system functions. It also appears to help reduce blood clotting. We do not know if these laboratory results will carry over to studies in people.

There have been some small human studies, including in people with AIDS. The results were inconclusive. In one study, cat's claw speeded the healing of people with herpes simplex virus (cold sores or genital herpes) and herpes zoster virus (shingles). A company that makes a purified version of cat's claw did this study. No independent researchers have gotten similar results.

Why Do People With HIV Use Cat's Claw?

Many people with HIV are attracted to herbs that are supposed to strengthen the immune system. However, the benefits of cat's claw have not yet been documented in humans. Also, it is possible that cat's claw could stimulate the immune system in ways that lead to progression of HIV disease. Without controlled studies, we don't know if it does anything, good or bad.

Health food companies promote cat's claw as a possible treatment for a wide range of health conditions. Some promotional materials call it a "miracle herb" and claim it is stronger than many other herbal products. These claims are not supported by careful research.

How Is Cat's Claw Used?

The traditional use of cat's claw was to make a tea from the inner bark of the vine. Health food companies offer cat's claw in capsules of powdered dried bark, as a liquid extract to use under the tongue, as tea bags, and as bulk bark and root to make into a tea. It is difficult to know the best dosage to use. In addition, there is no way to standardize the concentration of the active ingredients of cat's claw. It contains at least six chemicals that are supposed to have health benefits.

What Are the Side Effects?

Cat's claw may cause diarrhea and may lower blood pressure. Some cat's claw products say that they should not be used by pregnant women, or by people with immune disorders like multiple sclerosis.

How Does It Interact With Other Therapies?

Cat's claw may increase the blood levels of some protease inhibitors. Tell your health care provider if you are using herbal supplements.

How Do We Know It Works?

We do not know if cat's claw has any beneficial effects for people with HIV. There have been several laboratory studies that show promising results. However, very few people have taken cat's claw in careful scientific studies.

The Bottom Line

Cat's claw is an herbal product made from the bark and root of a vine that grows in Peru. Local native people have used it for hundreds of years to treat a variety of health problems.

Although some laboratory studies have shown promising results for cat's claw, there are very few studies in humans. Until there is more research on cat's claw, it is difficult to feel confident about its benefits or side effects.