Herb & supplement monograph

Cat's Claw Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Cat's Claw interacts with medications. The heart of this page is the interaction list — every drug Cat's Claw is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Cat's Claw is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Cat's Claw Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Cat's Claw drug interaction appears low for most people. None of the listed interactions are rated major, and nearly all are theoretical concerns drawn from lab or animal research rather than problems reported in people.

Interactions deserving the most attention

The combinations that deserve the most care involve closely monitored medicines. Compounds in cat's claw lowered blood pressure in animal studies, so it could add to the effect of blood pressure medications, including calcium channel blockers. In one human case report, cat's claw raised the levels of certain HIV medications (atazanavir, ritonavir, and saquinavir). Because it can stimulate the immune system, it may also work against immunosuppressants, and a theoretical bleeding risk exists with blood thinners.

What the rest of the list means

The list is long mainly because cat's claw may affect an enzyme the body uses to clear many common medications, so every drug processed that way is counted. Most of these predicted effects come from lab or animal research and have not been seen in people, so a listed interaction does not mean the combination is harmful.

Check your medications against Cat's Claw

Based on HelloPharmacist’s Cat's Claw interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Cat's Claw

964 medications have a known interaction with Cat's Claw, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Cat's Claw using our pharmacist-reviewed interaction data.

AI summaries are generated from our Cat's Claw interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Cat's Claw combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Cat's Claw affects

Every type of medication (drug category) Cat's Claw is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 6 drug categories Cat's Claw interacts with

Anticoagulant/antiplatelet DrugsAntihypertensive DrugsCalcium Channel BlockersCytochrome P450 3a4 (cyp3a4) SubstratesImmunosuppressantsNirmatrelvir/ritonavir (paxlovid)

Anticoagulant/Antiplatelet Drugs

Theoretically, cat's claw may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Cat's claw contains rhynchophylline and isorhynchophylline. Animal research suggests that these alkaloids can inhibit platelet aggregation. This interaction has not been reported in humans.

Likelihood Possible Evidence D

Antihypertensive Drugs

Theoretically, taking cat's claw with antihypertensive drugs might increase the risk of hypotension.
Cat's claw contains rhynchophylline. In vitro and animal research suggests that rhynchophylline can lower blood pressure. This interaction has not been reported in humans.

Likelihood Probable Evidence D

Calcium Channel Blockers

Theoretically, taking cat's claw with calcium channel blockers might increase the risk of hypotension.
Cat's claw contains various alkaloids, including rhynchophylline, isorhynchophylline, corynoxeine, and isocorynoxiene. Animal research suggests that these alkaloids can lower blood pressure by acting as calcium channel blockers. This interaction has not been reported in humans.

Likelihood Probable Evidence D

Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, cat's claw might increase or decrease the levels and effects of drugs metabolized by CYP3A4.
Cat's claw may affect the clearance of drugs metabolized by CYP3A4. In vitro research shows that cat's claw can inhibit CYP3A4 enzymes. In one case report, a patient taking cat's claw (at an unspecified dose) experienced increased serum levels of atazanavir, ritonavir, and saquinavir, all of which are CYP3A4 substrates. Levels returned to normal 15 days after discontinuation of the cat's claw supplement, suggesting inhibition of CYP3A4 by cat's claw. In contrast, animal research suggests that rhynchophylline, an alkaloid contained in cat's claw, induces CYP3A expression and accelerates the metabolism of nirmatrelvir, the active component in the nirmatrelvir/ritonavir combination product.

Likelihood Possible Evidence D

Immunosuppressants

Theoretically, cat's claw might interfere with immunosuppressive therapy.
In human and laboratory research, cat's claw has been shown to have immunostimulating activity. It stimulates phagocytosis and increases respiratory cellular activity and the mobility of leukocytes. Theoretically, this could interfere with the activity of immunosuppressant medications.

Likelihood Possible Evidence D

Nirmatrelvir/Ritonavir (Paxlovid)

Theoretically, cat's claw may decrease the levels of nirmatrelvir.
Cat's claw contains rhynchophylline. Animal research suggests that this alkaloid induces CYP3A expression, thereby accelerating the metabolism of nirmatrelvir, the active component in the nirmatrelvir/ritonavir combination product. This interaction has not been reported in humans.

Likelihood Possible Evidence D

Monograph

Cat's Claw: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Cat's claw is a South American vine traditionally used for inflammation, joint pain, and immune support. Some small studies hint it may help with arthritis symptoms, but the overall evidence is limited and not strong enough to confirm clear benefits. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Scientific name: Uncaria tomentosa
Family: Rubiaceae
Part used: Bark and root
Common forms: Capsules, tablets, liquid extracts/tinctures, tea

People commonly use it for

Osteoarthritis and rheumatoid arthritis
Inflammation
Immune support
Digestive complaints
General wellness/tonic

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated short-term in healthy adults, but long-term safety is not well studied.

PregnancyPossibly Unsafe

When used orally. There is concern that cat's claw might be unsafe based on its traditional use as a contraceptive; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Cat's claw is a woody climbing vine that grows in the tropical rainforests of South and Central America, especially in the Amazon region of Peru. It gets its name from the small, curved thorns along the vine that look like a cat's claws.

The bark and root have been used for many years in traditional Amazonian medicine for a wide range of problems, including inflammation, joint pain, stomach trouble, and to support the body's defenses. Most supplements come from the species Uncaria tomentosa, though a related species, Uncaria guianensis, is sometimes used too.

Today cat's claw is sold as capsules, tablets, liquid extracts, and teas, often marketed for joint health and immune support.

How it works

Cat's claw contains several natural compounds that researchers think may be responsible for its effects. These include oxindole alkaloids, as well as plant compounds such as polyphenols, tannins, and quinovic acid glycosides.

In laboratory and animal studies, extracts of cat's claw appear to lower certain markers of inflammation and may influence how immune cells behave. Some researchers have also looked at possible antioxidant effects.

It is important to know that most of this information comes from test-tube and animal research. We do not fully understand how, or whether, these effects work the same way in the human body.

Effectiveness

Does Cat's Claw work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 15 uses evaluated

15 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Cat's Claw, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 15 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Allergic rhinitis (hay fever)