About Cat's Claw

Woody vine from the Amazon rainforest, named for its hooked thorns. Taken mostly for joint pain and immune support.

Effectiveness Scores

Joint Health Adults with arthritis: 5.0/10.
Cat's claw appears to lower TNF-alpha, one of the main signals that drives swelling and pain in joints. Calming that signal is the idea behind using it for arthritis.
Why this rating: Two small trials found real improvements. In one, 45 people with knee osteoarthritis had less pain during activity within a week, though pain at night and swelling didn't change. In the other, 40 people with rheumatoid arthritis who added cat's claw to their usual medication had about half as many painful joints after six months. But the two studies used two different species of cat's claw, in two different kinds of arthritis, and neither has been repeated in over twenty years. Worth trying alongside your current care, not in place of it.
Immune Support: 4.0/10 (moderate evidence).
Cat's claw seems to do two things at once. It lowers some of the signals that drive inflammation while boosting other parts of the immune system, like the cells that fight infection.
Why this rating: Almost all of this comes from lab and animal research. The few human studies are small, and they measured things like DNA repair or response to a vaccine rather than whether people actually got sick less. Many long-term users say they get fewer infections and feel more resilient, but no study has tested that. The same double action on the immune system is why people with autoimmune conditions need to be careful with it.
Cancer Treatment Support: 4.0/10 (moderate evidence).
Chemotherapy often knocks down white blood cells, which leaves people more exposed to infection. Cat's claw has been tested as a way to protect those cells during treatment.
Why this rating: Only two small trials exist, and they disagree. In 40 women with breast cancer, adding cat's claw to chemotherapy reduced the drop in white blood cells. In 43 people with colorectal cancer, the same dose made no difference at all. Neither result has been repeated, and cat's claw has never been shown to act on cancer itself. If you're in treatment, talk to your oncologist before adding it, since it can change how some drugs are processed.

Understanding Effectiveness Scores

What does this mean?

Our effectiveness scoring system is based on scientific research and evidence. Each health outcome is rated on a scale of 1-10, with higher scores indicating stronger scientific support for the supplement's effectiveness.

1/10: Scientific evidence concludes that supplement is ineffective for purpose
2/10: No scientific evidence supports effectiveness
3/10: Inconclusive results regarding effectiveness
4/10: Minimal research on effectiveness
5/10: Limited evidence of effectiveness; may have potential benefits, but more research is needed
6/10: Some evidence supports the supplement's effectiveness, but research is mixed
7/10: Moderate evidence shows the supplement is effective for certain purposes, with limited population studies
8/10: Solid evidence suggests the supplement is effective, but research is not as extensive as higher levels
9/10: Strong scientific evidence supports the supplement's effectiveness, but some minor gaps in research remain (e.g., limited long-term studies or specific populations).
10/10: Ample scientific research demonstrates that the supplement is both highly effective and safe for long-term use.

Form Variations

Pentacyclic (TOA-free) Uncaria tomentosa extract
A concentrated extract from the type of Uncaria tomentosa rich in pentacyclic alkaloids, the compounds tied to its immune effects. Labels often say "TOA-free." This is the form used in the rheumatoid arthritis trial.
Best for: matching the rheumatoid arthritis research, immune support
Freeze-dried Uncaria guianensis
This is what the knee osteoarthritis trial used.
Best for: matching the osteoarthritis research
Ground bark capsules
Plain dried bark, usually 300 to 500 mg per capsule. The most common store-bought form. The species and alkaloid type often aren't listed, so there's no way to know how closely it matches the studied forms.
Best for: general use

Dosage & Timeline

Standard Dosages

Dried stem bark extract: 20-350 mg
Capsules: 300-500 mg
Specific Condition Dosages:
- Knee osteoarthritis: 100 mg daily of freeze-dried Uncaria guianensis
- Rheumatoid arthritis: 30-60 mg daily Pentacyclic extract of Uncaria tomentosa
- Cancer Treatment Support: 300 mg daily of dry Uncaria tomentosa extract

Results Timeline

Knee pain: some relief within 1 week in the osteoarthritis trial
Rheumatoid arthritis: the trial measured results after 24 weeks

All other outcomes may be noticed after extended use or lack enough studies to establish an effectiveness timeline.

Safety Information

Pregnancy and breastfeeding: Avoid. Cat's claw may cause uterine contractions, and there isn't enough safety data for breastfeeding.
Autoimmune conditions: People with autoimmune disorders (e.g., lupus, multiple sclerosis, rheumatoid arthritis) should consult with a healthcare provider before using Cat's Claw, as it may stimulate the immune system and exacerbate these conditions.
Blood pressure and bleeding: Cat's Claw may have a blood pressure-lowering effect, so people with low blood pressure should use it cautiously. It may also increase the risk of bleeding when combined with anticoagulant medications like warfarin or aspirin.
Surgery: Due to its potential to interfere with blood clotting, it is recommended to stop taking Cat's Claw at least two weeks before scheduled surgery
Drug interactions: immunosuppressants, anticoagulants, and CYP3A4 substrates.

Side Effects

Common side effects:

Upset stomach or nausea
Diarrhea
Mild headache

Rare side effects:

Allergic reactions (e.g., skin rashes or itching)
Low blood pressure (in rare cases)
May interact with blood thinners, causing an increased risk of bleeding
Worsening of Parkinson's symptoms, reported in one case and reversed after stopping

While side effects are generally mild, long-term use or high doses may cause gastrointestinal discomfort. It is advisable to start with a lower dose to assess tolerance.

Usage Information

Most people take cat's claw for joint pain and immune support. Some people going through chemotherapy also use it to help their bodies handle treatment.

Cat's claw is a helper, not a treatment. It should not replace arthritis medication, and anyone in cancer treatment should talk to their oncologist before using it.

User Experience

Gathered from reviews and forum posts, not from studies. What people report tells you what to expect. It does not tell you whether something works.

Reviews are mostly positive, especially from people with arthritis. Common themes include "within 3 days pain almost went away" and getting back to lifting weights. Pain relief is usually noticed within the first week. People using it for immune support tend to say they feel a difference in 2 to 4 weeks.

Alternative Names

Uncaria tomentosa, Uña de gato

Cat's Claw