Cat’s claw: Evidence, Trial Doses & Interactions

About Cat’s claw

The inner bark and root of an Amazonian vine, containing oxindole alkaloids and quinovic acid glycosides. Two different species and two distinct alkaloid chemotypes are both sold under the same name.

The chemotype problem is central here: Uncaria tomentosa exists in pentacyclic and tetracyclic oxindole alkaloid forms, which are reported to have opposing effects on immune cells, and most retail products do not say which they contain. Human trials number in the low single digits and are small.

Sold as

Bark extract capsule, Tincture, Tea, Standardised alkaloid extract

Standardised to

Sometimes standardised to 1.3% oxindole alkaloids; chemotype rarely stated — a product without this marker may not resemble what was studied.

Also known as

Uña de gato, Uncaria guianensis, Samento

What the research used

The amounts, forms and durations published trials of Cat’s claw actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

Studied for Osteoarthritis and rheumatoid arthritis
100–300 mg
Not enough
Freeze-dried or standardised bark extract · 4–24 weeks
From two small trials, one in knee osteoarthritis and one in rheumatoid arthritis, each with fewer than 60 participants. That is not enough to establish a dose.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

Any time
Not enough
No timing has been studied. Trial protocols split the dose across the day for convenience.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

Immune function

Immune Health

Not enough evidence

There is not enough human research to say cat’s claw affects immune function. The immunological claims come from cell culture work on isolated alkaloids that behave differently depending on chemotype.

Not enough evidence. Not enough human research to say anything useful yet.

View the 3 sources

Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis.(opens in a new tab)
Randomised controlled trial · Inflammation research : official journal of the European Histamine Research Society ... [et al.] · 2001 · PMID 11603848
DNA repair enhancement of aqueous extracts of Uncaria tomentosa in a human volunteer study.(opens in a new tab)
Randomised controlled trial · Phytomedicine : international journal of phytotherapy and phytopharmacology · 2001 · PMID 11515717
Persistent response to pneumococcal vaccine in individuals supplemented with a novel water soluble extract of Uncaria tomentosa, C-Med-100.(opens in a new tab)
Randomised controlled trial · Phytomedicine : international journal of phytotherapy and phytopharmacology · 2001 · PMID 11515716

Deep research mode adds each paper’s own conclusion and stated limitations.

Joint comfort

Joint Health

Not enough evidence

Evidence is limited for cat’s claw and joint symptoms. Two small trials report modest reductions in pain scores, with no independent replication and no consistency in the extract used.

Not enough evidence. Not enough human research to say anything useful yet.

View the 3 sources

Randomized double blind trial of an extract from the pentacyclic alkaloid-chemotype of uncaria tomentosa for the treatment of rheumatoid arthritis.(opens in a new tab)
Randomised controlled trial · The Journal of rheumatology · 2002 · PMID 11950006
Efficacy and safety of freeze-dried cat's claw in osteoarthritis of the knee: mechanisms of action of the species Uncaria guianensis.(opens in a new tab)
Randomised controlled trial · Inflammation research : official journal of the European Histamine Research Society ... [et al.] · 2001 · PMID 11603848
Comparison of glucosamine sulfate and a polyherbal supplement for the relief of osteoarthritis of the knee: a randomized controlled trial [ISRCTN25438351].(opens in a new tab)
Randomised controlled trial · BMC complementary and alternative medicine · 2007 · PMID 17974032

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

Interaction
Immunosuppressants and antiretrovirals
Interacts withProtease inhibitors, ciclosporin, tacrolimus, CYP3A4 substrates
Cat’s claw inhibits CYP3A4 in laboratory work, and a case report describes raised protease-inhibitor levels in someone taking it alongside HIV therapy. It is also avoided with ciclosporin and tacrolimus because of its immune effects.
Avoid
Pregnancy
Cat’s claw has traditional use as a contraceptive and abortifacient in Peru. It should not be used in pregnancy or while trying to conceive.
Worth knowing
Kidney injury case report
Acute kidney injury has been reported in someone with lupus taking cat’s claw, and it is generally avoided in existing kidney disease.
Worth knowing
Species and chemotype confusion
Uncaria tomentosa and Uncaria guianensis are different plants sold under one common name, and the two alkaloid chemotypes of the former are reported to act in opposite directions on immune cells. Most labels state neither.
Interaction
Blood pressure and clotting
Interacts withAntihypertensives, anticoagulants
Reports of hypotension and effects on platelet function mean caution alongside antihypertensives and anticoagulants, and stopping before surgery.

Cat’s claw

What cat’s claw may help with

About Cat’s claw

What the research used

When it was taken

Any time

The evidence in depth

Immune function

Joint comfort

Things to know

Immunosuppressants and antiretrovirals

Pregnancy

Kidney injury case report

Species and chemotype confusion

Blood pressure and clotting

What cat’s claw may help with

About Cat’s claw

What the research used

When it was taken

🕐Any time

The evidence in depth

Immune function

Joint comfort

Things to know

Immunosuppressants and antiretrovirals

Pregnancy

Kidney injury case report

Species and chemotype confusion

Blood pressure and clotting

Any time