Drug & supplement interaction

Cat's Claw + Vemurafenib

Vemurafenib brand name: Zelboraf.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Cat's Claw has a moderate interaction with Vemurafenib. Theoretically, cat's claw might increase or decrease the levels and effects of drugs metabolized by CYP3A4.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Cat's Claw and Vemurafenib

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Vemurafenib

Vemurafenib falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Cat's Claw interacts with.

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.
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the situation with Zelboraf (vemurafenib) and cat's claw. Your body partly clears vemurafenib using a liver enzyme called CYP3A4, and cat's claw can tug on that same enzyme. The tricky part is that lab and animal studies point in both directions: in test-tube work cat's claw seems to slow CYP3A4 (which could let vemurafenib build up and raise the odds of side effects like rash, sun sensitivity, joint aches, or liver irritation), while one animal compound sped the enzyme up (which could weaken the drug).

So nobody can confidently predict which way it goes for you, and this is a cancer medicine where steady levels matter. Please don't start or stop anything on your own. Just run the cat's claw past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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
  2. 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
  3. 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

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Cat's Claw Also Interacts With Other Medications

Cat's Claw has 961 moderate known drug interactions in our database — the Vemurafenib one above is one of them. If you take anything else, check it against the full list below.

Moderate 961 No known interaction 1,869 (incl. Vemurafenib)
Taking anything else?

Check Another of Your Medications Against Cat's Claw

Covers the 2,830 medications we’ve checked against Cat's Claw. Pick one to open its full report.

From our Q&A

Questions About Cat's Claw or Vemurafenib

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Cat's Claw or Vemurafenib, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Vemurafenib

This page covers Cat's Claw only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Vemurafenib page lists 165 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 118 moderate · 39 minor.

From our pharmacist’s overview on the Vemurafenib page

“People taking vemurafenib (Zelboraf) for BRAF-positive melanoma often reach for immune boosters, herbal blends, and green teas, and this is one drug where those choices deserve real scrutiny before anything gets combined. Of the 165 supplement ingredients with an interaction on file, 8 are rated major, and the biggest cluster (121 ingr…”

Reviewed by 2 · Jul 18, 2026

Open the Vemurafenib interaction page

One more smart check

Taking Cat's Claw as Part of a Dietary Supplement Product? Check It for Interactions

We hold 910 real supplement products containing Cat's Claw, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cat's Claw. Your product may carry other ingredients that interact with Vemurafenib too, on top of Cat's Claw — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Cat's Claw and Vemurafenib Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Cat's Claw
Top 25%

#223 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Vemurafenib
Top half

#1,133 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Cat's Claw

What is Cat's Claw?

Cat's Claw
  • Osteoarthritis and rheumatoid arthritis
  • Inflammation
  • Immune support
  • Digestive complaints
  • General wellness/tonic

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.

Read the full Cat's Claw monograph & all interactions
Medication

About Vemurafenib

What Is Vemurafenib Used For?

Brand name: Zelboraf

Zelboraf (vemurafenib) is used to treat adults with unresectable or metastatic melanoma — meaning melanoma that cannot be surgically removed or has spread — when the tumor tests positive for a specific genetic change called the BRAF V600E mutation. An FDA-approved test must confirm this mutation before starting treatment.

Zelboraf is also approved for patients with Erdheim-Chester Disease (ECD), a rare condition where abnormal immune cells build up in organs, when that disease carries a BRAF V600 mutation. Zelboraf is not for patients whose melanoma has normal (wild-type) BRAF, as it may actually promote tumor growth in that setting.

See full Vemurafenib drug information
Keep checking

Other Drugs & Cat's Claw

Browse every other medication we’ve checked against Cat's Claw — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
961Moderate
0Minor
1,868No known interaction
961 Moderate 1,868 No interaction
Moderate

961 interactions

Showing 60 of 961 moderate interactions — see all 961 on the Cat's Claw page.

No interaction 1,868 drugs checked — show the list

We also checked Cat's Claw against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,868 medications checked with no known interaction — see the full Cat's Claw list.

See the full Cat's Claw interactions page
See every supplement checked against Vemurafenib, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

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

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

Keep exploring
Cat's Claw monograph › Uses, safety, and every drug interaction in one place Vemurafenib supplement interactions › Every supplement checked against Vemurafenib, ranked by severity Vemurafenib drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Cat's Claw and Vemurafenib Together: Common Questions

Can you take Cat's Claw with Vemurafenib?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Cat's Claw and Vemurafenib interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Vemurafenib and Cat's Claw?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.