Drug & supplement interaction

Cat's Claw + Amlodipine Besilate

Amlodipine Besilate brand name: Istin.

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

Amlodipine Besilate falls into 3 drug categories that Cat's Claw can interact with; the most serious is rated moderate. Theoretically, taking cat's claw with antihypertensive drugs might increase the risk of hypotension.

Read the full interaction report
SeverityModerate
LikelihoodProbable
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Cat's Claw and Amlodipine Besilate

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Cat's Claw interacts with whole categories of medication. Amlodipine Besilate falls into 3 of those categories, so it can interact with Cat's Claw in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIHYPERTENSIVE DRUGS

1 of 3

Why this applies to Amlodipine Besilate

Amlodipine Besilate falls under ANTIHYPERTENSIVE DRUGS — the group Cat's Claw interacts with.

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.
Severity Moderate Likelihood Probable Evidence D

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..

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

Here's the simple version: amlodipine is a calcium channel blocker that already works to lower your blood pressure. Cat's claw contains a compound called rhynchophylline that, in lab and animal studies, also seems to nudge blood pressure down. So the worry is that stacking the two could push your numbers a little lower than intended.

If that happened, you might feel dizzy, lightheaded, tired, or a bit unsteady when you stand up quickly. I want to be honest though: this is a theoretical concern based on test-tube and animal work, and it has not actually been reported in people. That doesn't mean ignore it. If you take amlodipine and want to try cat's claw, check with your pharmacist or doctor first, and keep an eye on how you feel.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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
  2. 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
  3. Hemingway, S. R. and Phillipson, J. D. Proceedings: Alkaloids from S. American species of Uncaria (Rubiaceae). J.Pharm.Pharmacol. 1974;26 Suppl:113P.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Amlodipine Besilate also falls under 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.
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

Your blood pressure medicine, amlodipine, is cleared from your body by a liver enzyme called CYP3A4. Cat's claw seems to tug on that same enzyme, though the evidence here is thin and mostly from lab and animal work, plus one case report with different drugs. So this is more of a theoretical concern than a proven problem.

If cat's claw slows that enzyme, amlodipine could build up a bit, which might mean more dizziness, flushing, headache, swollen ankles, or a lower-than-usual blood pressure. Confusingly, some animal data hint it could speed clearance instead, which might weaken the effect. Because we can't be sure which way it goes, please don't start or stop anything on your own. Just check in with your pharmacist or doctor 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
Moderate

CALCIUM CHANNEL BLOCKERS

3 of 3

Amlodipine Besilate also falls under 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.
Severity Moderate Likelihood Probable Evidence D

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..

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

Here's the simple version: amlodipine (Istin) is a calcium channel blocker that relaxes your blood vessels to bring blood pressure down. Lab and animal studies suggest cat's claw has natural compounds that act in a similar way, gently nudging blood pressure lower too. Put the two together and, in theory, their effects could stack up.

If that happened, you might notice signs of blood pressure dropping too far, things like dizziness, lightheadedness when you stand, swollen ankles, or feeling unusually tired. I want to be honest, though: this has only been seen in lab and animal research, never confirmed in people, so it's more a caution than a proven problem. Please don't stop either one on your own. Just give your pharmacist or doctor a heads-up so they can keep an eye on your readings.

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

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 Amlodipine Besilate one above is among them. If you take anything else, check it against the full list below.

Moderate 961 No known interaction 1,869 (incl. Amlodipine Besilate)
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 Amlodipine Besilate

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 Amlodipine Besilate, 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 Amlodipine Besilate

This page covers Cat's Claw only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Amlodipine Besilate page lists 232 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Coleus (major) and Grapefruit (major).

By severity: 7 major · 183 moderate · 42 minor.

From our pharmacist’s overview on the Amlodipine Besilate page

“People take amlodipine besilate (Istin) to lower blood pressure, then reach for fish oil, CBD, or a morning glass of grapefruit juice without a second thought, and this is a list that deserves genuine care. Seven of its 232 supplement interactions are rated major, with grapefruit the everyday standout because it blocks the enzyme (CYP3…”

Reviewed by 2 · Jul 18, 2026

Open the Amlodipine Besilate 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 Amlodipine Besilate 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 Amlodipine Besilate 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%

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

29 days ago today
Medication Amlodipine Besilate
Top 5%

#75 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
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 Amlodipine Besilate, 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 Amlodipine Besilate supplement interactions › Every supplement checked against Amlodipine Besilate, ranked by severity 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 Amlodipine Besilate Together: Common Questions

Can you take Cat's Claw with Amlodipine Besilate?
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.
Why are there 3 interactions listed for Cat's Claw and Amlodipine Besilate?
Amlodipine Besilate belongs to more than one drug category, and Cat's Claw interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Cat's Claw and Amlodipine Besilate 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 Amlodipine Besilate and Cat's Claw?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.