Drug & supplement interaction

Devil's Claw + Nelfinavir Mesylate

Nelfinavir Mesylate brand name: Viracept.

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

Nelfinavir Mesylate falls into 3 drug categories that Devil's Claw can interact with; the most serious is rated moderate. Theoretically, devil's claw might increase levels of drugs metabolized by CYP2C19.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Devil's Claw and Nelfinavir Mesylate

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

Why Are There 3 Interactions?

Devil's Claw interacts with whole categories of medication. Nelfinavir Mesylate falls into 3 of those categories, so it can interact with Devil'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

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 3

Why this applies to Nelfinavir Mesylate

Nelfinavir Mesylate falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Devil's Claw interacts with.

Theoretically, devil's claw might increase levels of drugs metabolized by CYP2C19.
In vitro research shows that devil's claw might inhibit CYP2C19, although this has not been reported in humans.
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 simple version: your body uses an enzyme called CYP2C19 to help clear nelfinavir (Viracept). In lab dish studies, devil's claw appeared to slow that enzyme down a bit. If that happened in real life, more nelfinavir could linger in your blood, which in theory could mean more of its usual side effects like diarrhea, nausea, gas, or stomach upset. Nelfinavir works as-is (it is not a prodrug that needs activating), so this is about levels going up, not down.

The important caveat: this is only test-tube evidence and has never been seen in actual patients. Since nelfinavir is an HIV medicine where steady levels really matter, please don't start or stop anything on your own. Just run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Nelfinavir Mesylate also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, devil's claw might increase levels of drugs metabolized by CYP3A4.
In vitro research shows that devil's claw might inhibit CYP3A4, although this has not been reported in humans.
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 body relies on a liver enzyme called CYP3A4 to break down nelfinavir (Viracept). Lab studies hint that devil's claw might slow that enzyme down a bit. If it did, nelfinavir could build up a little higher than usual, which in theory might mean more of its typical side effects like diarrhea, nausea, gas, or stomach upset.

Here's the reassuring part: this concern comes only from test-tube research, not from real people, so it may not happen at all in your body. Still, since keeping HIV medicine at the right level matters, I'd run your devil's claw plans past your pharmacist or HIV doctor first rather than starting or stopping anything on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
Minor

P-GLYCOPROTEIN SUBSTRATES

3 of 3

Nelfinavir Mesylate also falls under P-GLYCOPROTEIN SUBSTRATES.

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 gist for your HIV medicine. Your body uses a kind of cellular bouncer called P-glycoprotein to push certain drugs, including nelfinavir, back out of cells. In test-tube studies, devil's claw seems to slow that bouncer down. In theory, that could let a little more nelfinavir hang around inside your cells, which might bump up side effects like diarrhea, nausea, gas, or stomach upset.

I want to be honest with you though: this is only lab data, the interaction is rated minor, and we genuinely don't know if it matters in real people. Nelfinavir is not a prodrug, so this isn't about it working better or worse for HIV. Still, since keeping HIV treatment steady is so important, please run devil's claw by your pharmacist or doctor before adding it.

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 730 moderate, 73 minor known drug interactions in our database — the Nelfinavir Mesylate one above is among them. If you take anything else, check it against the full list below.

Moderate 730 Minor 73 No known interaction 2,027 (incl. Nelfinavir Mesylate)
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 Nelfinavir Mesylate

This page covers Devil's Claw only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nelfinavir Mesylate page lists 153 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 113 moderate · 37 minor.

From our pharmacist’s overview on the Nelfinavir Mesylate page

“Nelfinavir mesylate (Viracept) treats HIV, where a steady drug level is what keeps the virus suppressed, so this is a list to read with real care before adding any supplement. Three of the 153 ingredients on file rate major, and St.”

Reviewed by 2 · Jul 18, 2026

Open the Nelfinavir Mesylate 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 Nelfinavir Mesylate 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 Nelfinavir Mesylate 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%

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

29 days ago today
Medication Nelfinavir Mesylate
Top half

#1,346 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
Medication

About Nelfinavir

What Is Nelfinavir Used For?

Brand name: Viracept

Viracept (nelfinavir) is used to treat HIV-1 infection. It is always taken alongside other antiretroviral (HIV-fighting) medicines — it is not used alone.

Viracept tablets are approved for adults, adolescents 13 years and older, and children aged 2 to less than 13 years.

See full Nelfinavir drug information
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
730Moderate
73Minor
2,026No known interaction
730 Moderate 73 Minor 2,026 No interaction
Moderate

730 interactions

Showing 60 of 730 moderate interactions — see all 730 on the Devil's Claw page.

Minor

73 interactions

Showing 60 of 73 minor interactions — see all 73 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 Nelfinavir Mesylate, 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 Nelfinavir Mesylate supplement interactions › Every supplement checked against Nelfinavir Mesylate, ranked by severity Nelfinavir 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 Devil's Claw and Nelfinavir Mesylate Together: Common Questions

Can you take Devil's Claw with Nelfinavir Mesylate?
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 Devil's Claw and Nelfinavir Mesylate?
Nelfinavir Mesylate belongs to more than one drug category, and Devil'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 Devil's Claw and Nelfinavir Mesylate 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 Nelfinavir Mesylate 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.