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Dietary supplement

Cat's Claw Extract Ingredients & Drug Interactions

by NOW

Cat's Claw Extract label
See full label image
Capsule Category: Botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Cat's Claw Extract 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 Extract is a dietary supplement by NOW 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 extract. 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 Extract by NOW

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

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HelloPharmacist Scorecard of Cat's Claw Extract by NOW

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 extract. Cat's claw is a vine from the Amazon rainforest traditionally used to support immune and inflammatory health, though evidence for specific conditions is limited.

The capsule also contains inactive ingredients (fillers and binders) including vegetable polysaccharide, microcrystalline cellulose, magnesium stearate, and stearic acid.

Does it work?

Not established
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 established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use — see Cat's Claw's own graded uses on its monograph.

Why this rating?
  • The label markets this product for: Immune system support.
  • We looked for evidence on: Inflammatory bowel disease (IBD), Osteoarthritis, Rheumatoid arthritis (RA), General wellness, Inflammation management, Joint health.
  • The closest evidence on file: Cat's Claw is rated "Insufficient Reliable Evidence To Rate" for Inflammatory bowel disease (IBD) (Natural Medicines).
  • Also on file: Cat's Claw is rated "Insufficient Reliable Evidence To Rate" for Osteoarthritis, Rheumatoid arthritis (RA).

The evidence for cat's claw is not established for the uses we have data on. The product has been studied for allergic rhinitis (hay fever), Alzheimer disease, asthma, osteoporosis, cancer, and chronic fatigue syndrome, but all of these carry insufficient evidence ratings—meaning the science isn't there yet to say whether it works.

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 by healthy adults, but we don't know much about long-term safety. In one clinical trial of patients with advanced cancer, a small number experienced anemia, low white blood cell counts (leukopenia), low platelet counts (thrombocytopenia), headache, fatigue, insomnia, and nerve damage (neuropathy)—though it's unclear whether these were from the disease itself or the supplement.

Several case reports have linked cat's claw to kidney injury, particularly in people with pre-existing conditions like lupus or a history of cancer. The safety data advises against cat's claw during pregnancy because of its traditional use as an abortifacient and lack of safety testing.

There isn't enough data to know whether it's safe while breastfeeding—talk with your pharmacist or doctor for personalized advice.

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.

Before taking NOW's Cat's Claw Extract, double-check these medication types with your pharmacist: blood thinners (anticoagulants and antiplatelet drugs), blood pressure medications (antihypertensive drugs and calcium channel blockers), immunosuppressants, CYP3A4-metabolized drugs, and the COVID-19 antiviral Paxlovid. All of these have Moderate interactions documented with cat's claw.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Moderate medication interactions have been identified, and safety information is well characterized.

Cat's claw may appeal to those interested in traditional immune support, but the evidence for specific health conditions isn't established yet. If you take blood pressure medications, blood thinners, immunosuppressants, or drugs metabolized by CYP3A4, you should check your exact medications before starting.

Pregnant and breastfeeding individuals should avoid it. Talk with your pharmacist about whether this product fits your situation.

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 Jan 25, 2020.

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 Extract, straight from the product label.

Brand NOW
Barcode (UPC) 733739046161
Net contents 60 Veg Capsule(s)
Market status On market
Date entered into DSLD Jan 25, 2020
DSLD ID 211139
Product type Botanical
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Vegan, Vegetarian, Kosher, Adult Male (18-50 Years), Gluten Free, Dairy Free
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 Extract by NOW, 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:
1 Veg Capsule(s)
Maximum serving Sizes:
1 Veg Capsule(s)
UPC/BARCODE
733739046161
IngredientAmount% DV
Cat's Claw extract334 mg--

Other ingredients: Vegetable Polysaccharide, Microcrystalline Cellulose, Magnesium Stearate, Stearic Acid

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.
Suggested/Recommended/Usage/Directions

Suggested Usage: Take 1 capsule 1 to 2 times daily, preferably with food.

Formula

NOW Cat's Claw Extract has the highest bark quality of authentic Uncaria tomentosa, an exciting herbal discovery from the Peruvian rainforest. Also called una de gato, it has been used for hundreds of years by the native Ashanica Indians.

10:1 concentrate 1.5% standardized extract

Triangle K

FDA Disclaimer Statement

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Precautions

Caution: For adults only.

Not recommended for pregnant/nursing women. Consult physician if taking medication or have a medical condition.

Keep out of reach of children.

Not manufactured with yeast, wheat, gluten, soy, milk, egg, fish, shellfish or tree nut ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.

Formulation

Natural color variation may occur in this product.

Immune system support

Non GMO

Vegetarian/vegan

Not manufactured with yeast, wheat, gluten, soy, milk, egg, fish, shellfish or tree nut ingredients.

Seals/Symbols

Non GMO Project Verified nongmoproject.org

Triangle K

GMP Quality Assured

FDA Statement of Identity

A Dietary Supplement

General Statements

Botanicals/herbs Family owned since 1968.

Storage

Store in a cool, dry place after opening.

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

See for yourself

Cat's Claw Extract by NOW label

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

Cat's Claw Extract 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 Extract by NOW

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

Serving size1 Veg Capsule(s) Dosage formCapsule Amounts shown are per serving.

Cat's Claw extract

Interacts with
962 drugs
334 mg per serving Form: Total Oxindole Alkaloids

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 extract monograph & interactions

Other (inactive) ingredients: Vegetable Polysaccharide, Microcrystalline Cellulose, Magnesium Stearate, Stearic Acid. These complete the product’s ingredient list but are not active constituents.

Interaction report

Cat's Claw Extract by NOW Drug Interactions

Want to check YOUR meds against Cat's Claw Extract?

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 extract 962

Individual Drug Interactions

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

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

Each ingredient & the kinds of drugs it affects

For each ingredient in Cat's Claw Extract 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 Claw extract6 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 extract full monograph & interactions
The maker

Brand information

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

NOW

See all NOW products
Name
NOW Foods
Street Address
395 S. Glen Ellyn Rd.
City
Bloomingdale
State
IL
ZipCode
60108
Web Address
nowfoods.com
Pharmacist Counseling Corner

Cat's Claw Extract by NOW: Common Questions

Does Cat's Claw Extract by NOW interact with any medications?
Yes. Based on its ingredients, Cat's Claw Extract 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 Extract 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.
What is cat's claw and where does it come from?
Cat's claw is a vine native to the Amazon rainforest, traditionally used in herbal medicine. Its name comes from its claw-shaped thorns. This extract contains the concentrated active compounds from the plant.
Can I take this while I'm on blood pressure medication?
Cat's claw contains compounds that may lower blood pressure, so combining it with antihypertensive drugs or calcium channel blockers could theoretically increase the risk of hypotension (low blood pressure). It hasn't been reported in humans, but you should check with your pharmacist before adding this to your routine.
Is cat's claw safe during pregnancy?
No. The safety data advises against cat's claw during pregnancy because of its traditional use as an abortifacient and the lack of safety studies. If you're pregnant or planning to become pregnant, skip this product.
What side effects should I watch for?
In a clinical study, a small number of patients experienced anemia, low white blood cell counts, low platelet counts, headache, fatigue, insomnia, and nerve pain. Several cases have also linked cat's claw to kidney injury, especially in people with pre-existing conditions. Stop and contact your doctor if you notice unusual bruising, persistent fatigue, or changes in urination.
Does cat's claw actually work for the conditions advertised?
The evidence isn't established yet. Cat's claw has been studied for hay fever, Alzheimer disease, asthma, osteoporosis, cancer, and chronic fatigue syndrome, but there's insufficient reliable evidence to say whether it works for any of them.
Can I take this with my immune-suppressing medication?
Cat's claw has immunostimulating activity—it boosts your immune response—which theoretically could interfere with immunosuppressive medications. Check with your pharmacist before using this product if you take any immune-suppressing drugs.

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 Extract label
Go deeper

The Full Monographs Behind Cat's Claw Extract’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 Extract'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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