Cat's Claw

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What is it

Cat's claw (Uncaria tomentosa or Uncaria guianensis), also called uña de gato, is a tropical vine native to the Amazon rainforest. Its inner bark and root have been used in traditional South American medicine for inflammation, immune support, and digestive issues. It is one of the more commonly used Amazonian medicinal plants in Western herbalism.

How it works

Cat's claw contains several classes of bioactive compounds, including oxindole alkaloids (pentacyclic and tetracyclic types), proanthocyanidins, quinovic acid glycosides, triterpenes, and sterols. The two main chemotypes contain different oxindole profiles: pentacyclic alkaloids (associated with immune-modulating effects) and tetracyclic alkaloids (with potentially competing CNS effects). Most modern supplements specify the pentacyclic chemotype. Proposed mechanisms include immune modulation through effects on cytokine production, anti-inflammatory effects via NF-kB inhibition, and antioxidant activity. Laboratory and animal studies have shown effects on multiple inflammatory pathways, with potential implications for inflammatory and autoimmune conditions. Some research has explored possible DNA repair effects, contributing to interest in immune and aging applications. Clinical evidence is most developed for inflammatory joint conditions, particularly osteoarthritis and rheumatoid arthritis, where some controlled trials show modest benefit. Other studied uses include immune support, chronic fatigue, and as an adjunct in cancer therapy, but clinical evidence is limited.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Osteoarthritis

Grade C

Moderate evidence

Small controlled trials of cat's claw extract suggest modest improvement in osteoarthritis pain and joint function. Effect sizes are modest but consistent in available studies.

Rheumatoid arthritis (adjunct)

Grade C

Moderate evidence

Some trials suggest modest benefit in rheumatoid arthritis when added to standard therapy. Use with caution given the immune-modulating effects.

Immune support

Grade C

Moderate evidence

Laboratory and some clinical evidence suggests immune-modulating effects. Translation to reduced infection rates or other clinically meaningful outcomes is limited.

Inflammation (general)

Grade C

Moderate evidence

Anti-inflammatory effects in laboratory and animal studies. Clinical translation to specific inflammatory conditions varies.

Cancer support (adjunct)

Grade D

Mixed evidence

Limited evidence as an adjunct in cancer therapy. Use only under oncology supervision due to potential immune effects and interactions.

4 commercial forms

Standardized pentacyclic alkaloid extract

Standardized to pentacyclic oxindole alkaloid content

Modern supplement form. Pentacyclic chemotype is preferred for immune applications.

AC-11 (branded extract)

Standardized hot-water extract

Patented extract used in research, particularly for immune and DNA repair applications.

Dried inner bark

Traditional whole-bark form

Used in traditional South American preparations and modern capsules.

Liquid extract / tincture

Alcohol-based extraction

Common in herbalist combination formulas.

Dosage

There is no established RDA. Traditional bark preparations use 250 to 1,000 mg of dried inner bark per day. Standardized extracts (often specifying pentacyclic oxindole alkaloid content or branded versions like AC-11) are commonly dosed at 100 to 300 mg per day. Clinical trials for arthritis have used 100 to 500 mg of standardized extract daily. Effects typically require weeks of consistent use.

When and how to take it

Cat's claw can be taken with or without food. Doses are typically divided two or three times daily. For arthritis applications, effects typically emerge over 4 to 8 weeks of consistent daily use. Some practitioners recommend cycling (months on, weeks off), though this is not strictly evidence-based.

Safety

Cat's claw is generally tolerated at typical doses. Side effects can include mild gastrointestinal upset, headache, dizziness, and skin rash. Less commonly, low blood pressure has been reported. Rare cases of acute kidney injury have been reported. There is no established Tolerable Upper Intake Level. Long-term high-dose safety has not been thoroughly evaluated.

Who should be cautious

Avoid in pregnancy and breastfeeding due to possible uterine effects and insufficient safety data. Avoid in people with autoimmune diseases (multiple sclerosis, lupus, rheumatoid arthritis) due to immune-stimulating effects, though some practitioners use it specifically in RA. Avoid in organ transplant recipients and those on immunosuppressants. Use caution in people with bleeding disorders or scheduled for surgery; discontinue at least two weeks before. People with low blood pressure should monitor.

Interactions

Cat's claw may interact with immunosuppressive medications (potentially reducing their effectiveness due to immune-stimulating effects). May potentiate antihypertensive medications. May affect anticoagulants and platelet function. Possible interaction with medications metabolized by cytochrome P450 enzymes. Can affect hormone metabolism. Discuss with a clinician before combining with prescription medications.

Frequently asked questions

Where does cat's claw get its name?⌄

The vine has thorns shaped like cat's claws, which it uses to climb trees in the rainforest. The Spanish name 'uña de gato' translates directly to 'cat's claw'.

What's the difference between pentacyclic and tetracyclic cat's claw?⌄

These are two chemotypes of Uncaria tomentosa with different oxindole alkaloid profiles. Pentacyclic is preferred for immune-modulating applications; tetracyclic may have competing CNS effects. Choose products specifying pentacyclic for most uses.

Can cat's claw help my arthritis?⌄

Small trials suggest modest benefit for osteoarthritis pain and function. Effects emerge over 4 to 8 weeks. It is not a substitute for evaluated arthritis treatment in moderate to severe disease.

Is cat's claw safe with autoimmune disease?⌄

Generally avoid in most autoimmune conditions due to immune-stimulating effects. Some practitioners use it in rheumatoid arthritis specifically, but discuss with a clinician familiar with herbal medicine.

Can I take cat's claw with my arthritis medication?⌄

Discuss with your prescriber. Cat's claw may affect immune-modulating medications and could potentially reduce effectiveness of immunosuppressants used in some forms of arthritis.

References

  • Wikidata: Uncaria tomentosa — Wikidata link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.