Overview

Cat’s claw refers to many species of thorny vines that grow in the Amazon rainforest. Dietary supplements that contain cat’s claw are usually made from the bark of the root or vine of Uncaria tomentosa. These products are used for many reasons, but their benefits are not well defined. Common side effects may include diarrhea or an upset stomach. Before taking cat’s claw, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is cat’s claw used for?

Cat’s claw is used for many reasons, but its benefits are not well defined. Some common reasons that people take cat’s claw include the following.

• Osteoarthritis
• Rheumatoid arthritis
• To improve immune function
• To reduce inflammation from various causes

Note: The FDA has not reviewed cat’s claw for safety and effectiveness. Learn more about dietary supplements here.

How does cat’s claw work (mechanism of action)?

Cat’s claw refers to many different species of thorny vines in the Uncaria genus. These vines have a long history of use in the Amazon rainforest, where they are known as uña de gato. Most dietary supplements that contain cat’s claw are made from the vine, the vine bark, or the root bark of Uncaria tomentosa, although some products may be made from a different species called U. guianensis.

Cat’s claw contains many different chemicals, such as oxindole alkaloids, tannins, and polyphenols. These chemicals may act as antioxidants and help reduce swelling (inflammation). This has led to interest in taking cat’s claw for conditions that are caused by inflammation, such as osteoarthritis and rheumatoid arthritis. But there is very little research on the use of cat’s claw for any purpose, and its benefits are not well defined.

Herbal products, such as cat’s claw, naturally contain many different chemicals. The amounts of each chemical in a specific cat’s claw product may vary. Some, none, or all of these chemicals may have certain effects on the body. These effects may change depending on how much of each chemical is found in the product you are using.

How should I store cat’s claw?

You should store cat’s claw as directed on the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of cat’s claw?

The most common side effects of cat’s claw are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.

• Diarrhea
• Upset stomach

There may be other side effects of cat’s claw that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of cat’s claw?

While less common, the most serious side effects of cat’s claw are described below, along with what to do if they happen.

Severe Allergic Reactions. Cat’s claw may cause allergic reactions, which can be serious. Stop taking cat’s claw and get help right away if you have any of the following symptoms of a serious allergic reaction.

• Breathing problems or wheezing
• Racing heart
• Fever or general ill feeling
• Swollen lymph nodes
• Swelling of the face, lips, mouth, tongue, or throat
• Trouble swallowing or throat tightness
• Itching or skin rash
• Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
• Nausea or vomiting
• Dizziness, feeling lightheaded, or fainting
• Stomach cramps
• Joint pain

Precautions

Who should not use cat’s claw?

Allergies to Ingredients. People who are allergic to any of the following should not use cat’s claw.

• Cat’s claw
• Uña de gato
• Uncaria guianensis
• Uncaria tomentosa
• Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific cat’s claw products they stock.

What should I know about cat’s claw before using it?

Cat’s claw is a dietary supplement. It cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are using, or use it as recommended by your health care provider.

Keep cat’s claw out of the reach of children.

Herbal products, such as cat’s claw, naturally contain many different chemicals. The amount of each chemical in a specific cat’s claw product can change for many reasons, including the area where the plant was grown, the weather during growth, the time of year it was harvested, and the way the plant was processed after harvesting. If you switch to a new bottle or a different brand, you may not have the same effects or side effects because of this variability. Talk to your health care provider if you have questions or concerns.

Cat’s claw is available in many forms, including liquid extract, tablets, capsules, or tea. Each of these forms may contain different amounts of the chemicals that are naturally found in the plant.

Cat’s claw products may be made from two different species —U. tomentosa or U. guianensis. These species are not the same and may contain different chemicals that can cause different effects and side effects. It is important to read the label to confirm which species was used to make that product.

The FDA has not tested cat’s claw products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using cat’s claw?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if cat’s claw is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions.Tell your health care provider if you have any of the following.

• An autoimmune condition
• Kidney problems
• Liver problems

Other Medicines and Supplements.Cat’s claw may interact with other medicines and supplements. Before taking cat’s claw, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how cat’s claw could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if cat’s claw passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does cat’s claw interact with foods or drinks?

There are no known interactions between cat’s claw and foods or drinks.

It is unknown if drinking alcohol will affect cat’s claw.

Does cat’s claw interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking cat’s claw.

• A blood thinner, which is a medicine used to treat or prevent blood clots
• A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which is in many prescription and OTC products for pain, swelling, and fever
• An antiplatelet medicine, such as aspirin/dipyridamole, cilostazol, clopidogrel (Plavix), or ticagrelor (Brilinta), which is a medicine used to prevent blood clots

The interactions between cat’s claw and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with cat’s claw is incomplete. Always check with your health care provider before taking cat’s claw with any medicines.

Dosing

What should I do if I accidentally use too much cat’s claw?

If you or someone else has used too much cat’s claw, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

Cat’s claw comes in many different doses and forms. Read the product label closely and speak to a health care provider about how to take cat’s claw safely. Do not take double or extra doses, even if you miss a dose.