Scientific Name: Cat's Claw
Other Names: Peruvian Cat's Claw, Samento, Saventaro, Una de Gato, Uncaria guianensis, Uncaria tomentosa

Who is this for?

Uses

Note: In Mexico and the southwestern United States, a plant with the Latin name of Acacia gregii, is known as cat's claw acacia or catclaw acacia. This shrubby tree is not the same as the long South American vine (Uncaria guianensis or Uncaria tomentosa) that produces the cat's claw used in medicine. Acacia gregii may contain a cyanide derivative which is extremely dangerous to take by mouth.

Probably the best-researched use of cat's claw is for the relief of arthritis pain. Results from animal studies and reports of human cases show that taking cat's claw by mouth may have anti-inflammatory effects for individuals with either osteoarthritis (the deterioration of joints due to wear and tear) or rheumatoid arthritis (an autoimmune disease in which the body's immune system attacks cartilage and synovial fluid in joints). Although the reasons are not all known, chemicals in cat's claw are believed to block the production of substances such as prostaglandins and tumor necrosis factor (TNF) alpha, which are involved in inflammation. Cat's claw appears to have little or no effect on swelling associated with arthritis, but some study participants who took it reported less pain during exercise. However, only a few human studies have been conducted and not all the results from those studies have been positive. More research is needed before cat's claw can be recommended for treating arthritis.

Cat's claw is also being studied for a number of other possible uses. Various chemicals that it contains are known to promote the loss of water from the body, relax smooth muscles, and widen small blood vessels in the hands and feet. All these effects may help to lower blood pressure. Cat's claw may have immune-system effects, as well. One theory is that chemicals in it promote the activity of macrophages, which are specialized white blood cells that absorb bacteria and tumor cells and also activate other immune system cells. In animal studies, cat's claw also appeared to promote the production of chemicals that extended the active lives of lymphocytes--white blood cells that fight infection. Lymphocyte production was not increased, however. In other laboratory studies, cat's claw extract stopped the spread of human lymphoma, leukemia, and breast cancer cells. In contrast, results from other laboratory studies may show that cat's claw actually caused certain cancers to spread faster. In one small human study and several animal studies, taking cat's claw may have promoted the repair of DNA damaged by chemotherapy or radiation. All the possible uses of cat's claw need much more research, including well-planned human studies.

In South America, cat's claw has a traditional use as a contraceptive. Possibly, very large doses may act as birth control, but no clinical studies have been conducted to verify either the effect or the dose. Potentially, though, cat's claw may cause miscarriage if is taken by mouth during pregnancy. Women who are pregnant should not take cat's claw.

Due to its potential effects on the immune system, cat's claw should not be taken by individuals who have received transplanted organs.

Even though cat's claw is thought to relieve rheumatoid arthritis, which is an autoimmune condition, it has not been studied for use in other autoimmune diseases. Taking cat's claw may produce unpredictable results for individuals who have other autoimmune conditions such as:

• Crohn's disease
• Multiple Sclerosis
• Psoriasis
• Systemic Lupus Erythematosus
• Type 1 diabetes

Precautions

Very little information is available on how cat's claw might affect an infant or a small child. Therefore, its use is not recommended while breast-feeding or during early childhood.

What side effects should I watch for?

Side effects associated with taking cat's claw include:

• Dizziness
• Headache
• Nausea

What interactions should I watch for?

Because it may enhance immune system function, cat's claw may interfere with the effects of drugs used to suppress the immune system after organ transplants or in other conditions. Taking cat's claw is not recommended for patients who take drugs such as:

• azathioprine (Imuran)
• CellCept
• cyclosporine (Neoral, Sandimmune)
• Prograf
• Rapamune
• Zenapax

Because it may be broken down by certain enzymes in the liver, cat's claw may possibly interfere with the use of prescription drugs that are processed by the same enzymes. Some of these drugs are:

• Allergy drugs such as fexofenadine
• Antifungal drugs such as itraconazole and ketoconazole
• Cancer drugs such as etoposide, paclitaxel, vinblastine, or vincristine
• Drugs for high cholesterol such as lovastatin
• Oral contraceptives

Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how cat's claw interacts with drugs, other herbals, and foods and the severity of those interactions, please use our Drug Interactions Checker to check for possible interactions.

Should I take it?

Although a bush called cat's claw acacia (Acacia gregii) grows in the desert areas of Mexico and the southwestern United States, the cat's claw (Uncaria guianensis or Uncaria tomentosa) used in medicine comes from countries in South America--particularly Peru. South American cat's claw is a long vine (called a liana in South America) that climbs into the highest parts of tropical trees. Reaching 100 feet or longer, it has thick woody stems and curved barbs at the places where the leaves attach to the stems. These claw-like projections allow the vine to attach to tree bark and also give the plant its name. Bright green, oval-shaped leaves, reddish colored stems, and stringy white (Uncaria tomentosa) or orange-red (Uncaria guianensis) flowers make the vines easy to spot. Cat's claw is difficult to cultivate, but it is farmed in some areas of Peru. It is usually planted from cuttings of the vine rather than from seeds.

Interest in the medicinal effects of cat's claw was raised in Europe and North America during the 1970s after it was mentioned prominently in a book about plants from South America. For use in medicine, the vines are generally at least 8 years old. Bark that is removed from the stems of cat's claw vines is dried and shredded. The de-barked vines die, but they may still be used for making rattan-like furniture.

Dosage and Administration

Herbal cat's claw (Uncaria guianensis or Uncaria tomentosa) should not be confused with a plant known as cat's claw acacia (or Acacia gregii) that grows in the United States and Mexico. Cat's claw acacia contains chemicals that may be harmful if swallowed. Individuals who have any question about the source of the cat's claw they plan to use, should not take it.

Cat's claw may be purchased in many different oral dosage forms that include liquids such as extracts and tinctures as well as solids such as capsules and tablets. Extracts and tinctures are concentrated liquid preparations usually made by soaking chopped or mashed plant parts in a liquid such as alcohol. Dried cat's claw bark is also sold for making tea. Amounts to use are not well defined although common doses in clinical trials have been 100 mg per day for osteoarthritis and 60 mg per day for rheumatoid arthritis. Some studies have used higher doses (350 mg to 500 mg per day) and daily doses as high as 10,000 mg (10 grams) have been reported among South Americans who take cat's claw as a general tonic. High doses of cat's claw have not been studied for possible side effects, however. Individuals who decide to use cat's claw should follow the directions on the package that is purchased.

Summary

Due to possible anti-inflammatory effects, cat's claw may help to relieve pain of arthritis. It may also be useful for lowering blood pressure and treating some cancers.

Risks

Pregnant women, organ transplant recipients, and individuals who have autoimmune conditions should avoid taking cat's claw.

Side Effects

Mild side effects such as dizziness and nausea have been attributed to taking cat's claw.

Interactions

Cat's claw may interfere with drugs that suppress the immune system and drugs that are processed by a certain set of enzymes.

Last Revised October 5, 2007

References

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Last Revised October 5, 2007

Note: The above information is not intended to replace the advice of your physician, pharmacist, or other healthcare professional. It is not meant to indicate that the use of the product is safe, appropriate, or effective for you.

In general, herbal products are not subject to review or approval by the U.S. Food and Drug Administration (FDA). They are not required to be standardized, meaning that the amounts of active ingredients or contaminants they contain may vary between brands or between different batches of the same brand. Not all of the risks, side effects, or interactions associated with the use of herbal products are known because few reliable studies of their use in humans have been done.

This information is provided for your education only. Please share this information with your healthcare provider and be sure that you talk to your doctor and pharmacist about all the prescription and non-prescription medicines you take before you begin to use any herbal product.

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