Drug & supplement interaction

Devil's Claw + Terfenadine

Terfenadine brand name: Seldane.

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

Devil's Claw has a minor interaction with Terfenadine. Theoretically, devil's claw might increase levels of P-glycoprotein substrates.

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

Devil's Claw and Terfenadine

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

Minor

P-GLYCOPROTEIN SUBSTRATES

Why this applies to Terfenadine

Terfenadine falls under P-GLYCOPROTEIN SUBSTRATES — the group Devil's Claw interacts with.

Theoretically, devil's claw might increase levels of P-glycoprotein substrates.
In vitro research shows that devil's claw inhibits P-glycoprotein, which transports many drugs out of cells. This might increase intracellular levels of P-glycoprotein substrates, although it is unclear if this effect would be clinically important.
Severity Minor 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 short version: terfenadine (old brand Seldane) relies on a cellular pump called P-glycoprotein to help move it out of your cells. Lab studies hint that devil's claw can slow that pump down a little. In theory, that could let more terfenadine linger in your body. That matters because terfenadine isn't a harmless antihistamine. At higher levels it can affect your heart's rhythm and cause a dangerous QT prolongation, which is exactly why it was pulled from the U.S. market years ago.

That said, this concern comes only from test-tube research, not from people, so we genuinely don't know if it plays out in real life. Still, given terfenadine's heart risk, I'd want you to clear this combo with your pharmacist or doctor first rather than guess.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Romiti N, Tramonti G, Corti A, Chieli E. Effects of Devil's Claw (Harpagophytum procumbens) on the multidrug transporter ABCB1/P-glycoprotein. Phytomedicine 2009;16:1095-100. 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

Devil's Claw Also Interacts With Other Medications

Devil's Claw has 731 moderate, 72 minor known drug interactions in our database — the Terfenadine one above is one of them. If you take anything else, check it against the full list below.

Moderate 731 Minor 72 No known interaction 2,027 (incl. Terfenadine)
Taking anything else?

Check Another of Your Medications Against Devil's Claw

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

Everything else you take

See Every Supplement That Interacts With Terfenadine

This page covers Devil's Claw only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Terfenadine page lists 65 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 · 42 moderate · 15 minor.

From our pharmacist’s overview on the Terfenadine page

“Terfenadine (Seldane) is an older antihistamine with a well-known heart rhythm hazard, and its supplement list warrants genuine caution. Eight of the 65 interactions on file are rated major, and the biggest danger is additive strain on the heart's electrical timing: 13 ingredients can prolong the QT interval the way terfenadine itself…”

Reviewed by 2 · Jul 18, 2026

Open the Terfenadine interaction page

One more smart check

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

We hold 585 real supplement products containing Devil's Claw, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Devil's Claw. Your product may carry other ingredients that interact with Terfenadine too, on top of Devil'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 Devil's Claw and Terfenadine 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 Devil's Claw
Top 25%

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

29 days ago today
Medication Terfenadine
Steady interest

#2,812 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 Devil's Claw

What is Devil's Claw?

Devil's Claw
  • Osteoarthritis pain
  • Lower back pain
  • Joint pain and stiffness
  • General inflammation
  • Digestive upset and loss of appetite

Devil's claw is a southern African plant used mainly for arthritis and back pain, and some studies suggest it may help ease these types of discomfort. The evidence is moderate at best, and product strength varies, so talk with your pharmacist or doctor before trying it, especially if you have a health condition or take medications.

Read the full Devil's Claw monograph & all interactions
Keep checking

Other Drugs & Devil's Claw

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

0Major
731Moderate
72Minor
2,026No known interaction
731 Moderate 72 Minor 2,026 No interaction
Moderate

731 interactions

Showing 60 of 731 moderate interactions — see all 731 on the Devil's Claw page.

Minor

72 interactions

Showing 60 of 72 minor interactions — see all 72 on the Devil's Claw page.

No interaction 2,026 drugs checked — show the list

We also checked Devil'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 2,026 medications checked with no known interaction — see the full Devil's Claw list.

See the full Devil's Claw interactions page
See every supplement checked against Terfenadine, 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
Devil's Claw monograph › Uses, safety, and every drug interaction in one place Terfenadine supplement interactions › Every supplement checked against Terfenadine, 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 Devil's Claw and Terfenadine Together: Common Questions

Can you take Devil's Claw with Terfenadine?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Devil's Claw and Terfenadine interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Terfenadine and Devil'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.