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Dietary supplement

Cat's Claw 500 mg Ingredients & Drug Interactions

by Thompson

Cat's Claw 500 mg label
See full label image
Capsule Category: Botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Cat's Claw 500 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Cat's Claw 500 mg is a dietary supplement by Thompson with 1 active ingredient. Its ingredients are commonly taken for osteoarthritis and rheumatoid arthritis, inflammation, immune support.Based on those ingredients, 962 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Cat's Claw. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Cat's Claw 500 mg by Thompson

Ask about any prescription or over-the-counter medication and we check it for interactions with Cat's Claw 500 mg by Thompson — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Cat's Claw 500 mg by Thompson

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 12, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: Cat's Claw (500 mg per capsule). It's a vine used in traditional medicine, and the supplement form captures its active alkaloids — compounds like rhynchophylline that appear to do the work.

The capsule itself is filled with gelatin and magnesium stearate, which are inactive ingredients used to hold everything together.

Does it work?

Couldn't assess
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

This is a single-ingredient Cat's Claw product and its label doesn't state a use — see Cat's Claw's own graded uses on its monograph.

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.

The evidence we hold doesn't establish that cat's claw works reliably for any condition — we have insufficient data on allergic rhinitis (hay fever), Alzheimer disease, asthma, osteoporosis, cancer, and chronic fatigue syndrome. That doesn't mean it's ineffective; it means large, well-controlled trials are missing or inconclusive.

If you're thinking about it for a specific health reason, talk with your pharmacist or doctor about what the research actually shows for your situation.

The evidence, ingredient by ingredient Cat's Claw

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Cat's claw is generally well tolerated in the short term for healthy adults, but we don't know much about long-term safety — it hasn't been studied that way. The safety data advises against use during pregnancy because of its traditional use as an abortifacient and the lack of safety information.

Avoid it while breastfeeding too, since we don't have enough data to know it's safe for nursing infants. In a clinical trial of patients with advanced solid tumors, some blood count changes showed up — anemia in 12% of patients, and leukopenia (low white blood cells) and thrombocytopenia (low platelets) each in 2%.

Because these were very sick patients with no other treatment options and there was no placebo group, it's unclear whether cat's claw caused these or the disease did. Case reports also link cat's claw to kidney injury in a few patients, though these are rare.

Headache, fatigue, insomnia, and nerve damage were reported in the same trial at low rates.

Side effects, ingredient by ingredient Cat's Claw

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Cat's Claw.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs.
  • For scale: 963 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check your medications against cat's claw before you use it, especially blood thinners and antiplatelet drugs (Moderate risk of bleeding), blood pressure medications and calcium channel blockers (Moderate risk of low blood pressure), drugs your liver breaks down through CYP3A4 (Moderate risk of changed drug levels), and Paxlovid (Moderate risk of lower antiviral levels). If you're on immunosuppressants, flag that too.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

Cat's Claw might be worth considering if you're looking for an immune or anti-inflammatory supplement and you've checked with your pharmacist first — especially important because of its interactions with blood pressure drugs, blood thinners, and medications your liver processes. Steer clear if you're pregnant, breastfeeding, on immunosuppressants, or taking Paxlovid.

Talk to your pharmacist about your full medication list before you start.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Aug 26, 2014.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Cat's Claw 500 mg, straight from the product label.

Brand Thompson
Barcode (UPC) 031315190728
Net contents 60 Capsule(s)
Market status On market
Date entered into DSLD Aug 26, 2014
DSLD ID 36512
Product type Botanical
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Cat's Claw 500 mg by Thompson, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
2 Capsule(s)
Maximum serving Sizes:
3 Capsule(s)
Servings per container
30
UPC/BARCODE
031315190728
IngredientAmount% DV
Cat's Claw1000 mg--

Other ingredients: Gelatin, Magnesium Stearate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
General Statements

Keep your licensed health care practitioner informed when using this product.

SINCE 1932

100% PURE

FRESH HEALTHY

SIX TIMES DAILY

Suggested/Recommended/Usage/Directions

Directions: Use only as directed. Take two or three capsules three times daily with meals or a glass of water.

Storage

Store in a cool, dry place.

Brand IP Statement(s)

Our own laboratory analysis guarantees purity and freshness of all Thompson(R) products.

(C)2008

General

1004214 0508

FDA Statement of Identity

DIETARY SUPPLEMENT

Precautions

WARNING: Do not use if safety seal is broken or missing.

Keep out of reach of children.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Cat's Claw 500 mg by Thompson label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Cat's Claw 500 mg label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Cat's Claw 500 mg by Thompson

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size2 Capsule(s) Dosage formCapsule Servings per container30 Amounts shown are per serving.

Cat's Claw

Interacts with
962 drugs
1000 mg per serving

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 arth...

Cat's Claw monograph & interactions

Other (inactive) ingredients: Gelatin, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Cat's Claw 500 mg by Thompson Drug Interactions

Want to check YOUR meds against Cat's Claw 500 mg?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
962Drugs
962 Moderate

Ingredients driving the most interactions

Cat's Claw 962

Individual Drug Interactions

The ingredients in Cat's Claw 500 mg interact with 962 drugs. Click any drug to see the details.

1 of the 1 ingredient in Cat's Claw 500 mg interact with drugs. Each result below shows which ingredient is responsible. Cat's Claw

Each ingredient & the kinds of drugs it affects

For each ingredient in Cat's Claw 500 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Cat's Claw6 drug types · 962 drugs

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
Cat's Claw full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Cat's Claw 500 mg, from the product label.

Thompson

See all Thompson products
Name
NutraPure, Inc.
Web Address
www.nutraceutical.com
Pharmacist Counseling Corner

Cat's Claw 500 mg by Thompson: Common Questions

Does Cat's Claw 500 mg by Thompson interact with any medications?
Yes. Based on its ingredients, Cat's Claw 500 mg has a known interaction with 962 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Cat's Claw 500 mg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Is cat's claw safe during pregnancy?
No — the safety data advises against it. Cat's claw has a history of traditional use as an abortifacient, and there's not enough safety information to know whether it's okay in pregnancy. Talk with your doctor before considering it.
Can I take this while breastfeeding?
No — there isn't enough safety data on cat's claw and nursing infants, so it's best to avoid it while breastfeeding. Check with your pharmacist or doctor if you're looking for alternatives.
Does cat's claw actually work for anything?
The evidence we hold doesn't establish that it works reliably for the conditions it's commonly used for — hay fever, Alzheimer disease, asthma, osteoporosis, cancer, or chronic fatigue. We simply don't have enough strong research yet. Your pharmacist can point you toward conditions with better evidence if you're treating something specific.
What are the side effects?
Short-term, it's generally well tolerated in healthy adults. But in a trial of very sick patients with advanced cancer, some experienced blood count changes like anemia and low white blood cells or platelets, plus headache, fatigue, insomnia, and nerve damage — though it's unclear if cat's claw caused these or the disease did. A few case reports also link it to kidney injury, though that's rare.
Can cat's claw interact with my blood pressure medication?
Yes — cat's claw may lower your blood pressure further on top of what your medication already does, raising the risk of blood pressure dropping too low. Same goes if you're on calcium channel blockers. Your pharmacist needs to review your exact drug before you start.
Will this interact with my blood thinner?
Possibly — animal research suggests cat's claw might slow platelet clumping, which could increase bleeding risk if you're on a blood thinner or aspirin. This hasn't been seen in humans yet, but it's worth checking with your pharmacist first.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Cat's Claw 500 mg label
Go deeper

The Full Monographs Behind Cat's Claw 500 mg’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Cat's Claw

Interacts with 962 drugs

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...

Read the full Cat's Claw monograph →
Sources

Sources & How We Checked

Cat's Claw 500 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 16 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Cat's Claw 16 references
  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
  3. Sandoval M, Charbonnet RM, Okuhama NN, et al. Cat's claw inhibits TNFalpha production and scavenges free radicals: role in cytoprotection. Free Radic Biol Med 2000;29:71-78.
  4. Müller AC, Kanfer I. Potential pharmacokinetic interactions between antiretrovirals and medicinal plants used as complementary and African traditional medicines. Biopharm Drug Dispos. 2011;32(8):458-70. PubMed
  5. Sheng, Y., Bryngelsson, C., and Pero, R. W. Enhanced DNA repair, immune function and reduced toxicity of C-MED-100, a novel aqueous extract from Uncaria tomentosa. J Ethnopharmacol. 2000;69(2):115-126. PubMed
  6. Lamm, S., Sheng, Y., and Pero, R. W. Persistent response to pneumococcal vaccine in individuals supplemented with a novel water soluble extract of Uncaria tomentosa, C-Med-100. Phytomedicine 2001;8(4):267-274.
  7. Sheng, Y., Li, L., Holmgren, K., and Pero, R. W. DNA repair enhancement of aqueous extracts of Uncaria tomentosa in a human volunteer study. Phytomedicine 2001;8(4):275-282.
  8. Chen, C. X., Jin, R. M., Li, Y. K., Zhong, J., Yue, L., Chen, S. C., and Zhou, J. Y. Inhibitory effect of rhynchophylline on platelet aggregation and thrombosis. Zhongguo Yao Li Xue.Bao. 1992;13(2):126-130.
  9. Flythe, J. E., Rueda, J. F., Riscoe, M. K., and Watnick, S. Silicate nephrolithiasis after ingestion of supplements containing silica dioxide. Am.J.Kidney Dis. 2009;54(1):127-130. PubMed
  10. Zhou, J. and Zhou, S. Antihypertensive and neuroprotective activities of rhynchophylline: the role of rhynchophylline in neurotransmission and ion channel activity. J.Ethnopharmacol. 10-28-2010;132(1):15-27. PubMed
  11. Zhou, J. Y. and Zhou, S. W. Isorhynchophylline: A plant alkaloid with therapeutic potential for cardiovascular and central nervous system diseases. Fitoterapia 2012;83(4):617-626. PubMed
  12. Hemingway, S. R. and Phillipson, J. D. Proceedings: Alkaloids from S. American species of Uncaria (Rubiaceae). J.Pharm.Pharmacol. 1974;26 Suppl:113P.
  13. Hilepo, J. N., Bellucci, A. G., and Mossey, R. T. Acute renal failure caused by 'cat's claw' herbal remedy in a patient with systemic lupus erythematosus. Nephron 1997;77(3):361. PubMed
  14. De Paula LCL, Fonseca F, Perazzo F, et al. Uncaria tomentosa (cat's claw) improves quality of life in patients with advanced solid tumors. J Altern Complement Med. 2015;21(1):22-30.
  15. Portalatin G, Shettigar S, Carrion-Rodriguez A, et al. Ketogenic-Diet Shake Containing Uncaria tomentosa-Associated Acute Interstitial Nephritis. Case Rep Nephrol Dial 2022;12(3):219-225.
  16. Lei S, Guo A, Lu J, et al. Activation of PXR causes drug interactions with Paxlovid in transgenic mice. Acta Pharm Sin B 2023;13(11):4502-4510. PubMed

See these in context on the Cat's Claw monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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