Drug & supplement interaction

White Pepper + Mephenytoin

Mephenytoin brand name: Mesantoin.

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

White Pepper has a moderate interaction with Mephenytoin. White pepper might increase levels of phenytoin.

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

White Pepper and Mephenytoin

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

Moderate

PHENYTOIN (Dilantin)

White pepper might increase levels of phenytoin. In humans, the piperine constituent of white pepper seems to increase absorption, slow elimination, and increase levels of phenytoin.
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 gist: mephenytoin is a close cousin of phenytoin, and both are seizure medicines that your body has to clear at a steady pace. The piperine in pepper may help your gut absorb more of the drug and slow how fast you get rid of it, which can nudge your blood levels up. With a drug like this, even small upward shifts can matter, since too much can bring on side effects like dizziness, drowsiness, unsteady walking, slurred speech, or jerky eye movements.

The good news is that this is mostly a theory based on how piperine behaves, not strong human proof, and a sprinkle of pepper on your food is very unlikely to cause trouble. The bigger question is concentrated piperine or black pepper supplements. Before adding one, check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Bano G, Amla V, Raina RK, et al. The effect of piperine on pharmacokinetics of phenytoin in healthy volunteers. Planta Med 1987;53:568-9. PubMed
  2. Velpandian T, Jasuja R, Bhardwaj RK, et al. Piperine in food: interference in the pharmacokinetics of phenytoin. Eur J Drug Metab Pharmacokinet 2001;26:241-7. 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

White Pepper Also Interacts With Other Medications

White Pepper has 975 moderate, 3 minor known drug interactions in our database — the Mephenytoin one above is one of them. If you take anything else, check it against the full list below.

Moderate 975 Minor 3 No known interaction 1,852 (incl. Mephenytoin)
Taking anything else?

Check Another of Your Medications Against White Pepper

Covers the 2,830 medications we’ve checked against White Pepper. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Mephenytoin

This page covers White Pepper only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mephenytoin page lists 215 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Kava (major).

By severity: 9 major · 178 moderate · 28 minor.

From our pharmacist’s overview on the Mephenytoin page

“Anyone taking mephenytoin (Mesantoin) for seizures should read this page with genuine care rather than as background noise. The biggest cluster of interactions piles sedation on top of a drug that already slows the nervous system, and alcohol, whether beer or wine, sits at the serious end of that group.”

Reviewed by 2 · Jul 18, 2026

Open the Mephenytoin interaction page

One more smart check

Taking White Pepper as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2 real supplement products containing White Pepper, each one broken down to its full ingredient list — and combination products often carry several ingredients besides White Pepper. Your product may carry other ingredients that interact with Mephenytoin too, on top of White Pepper — 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 White Pepper and Mephenytoin 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 White Pepper
Top half

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

29 days ago today
Medication Mephenytoin
Steady interest

#1,690 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 White Pepper

What is White Pepper?

  • Digestive upset
  • Seasoning and appetite support
  • Cough and cold remedies (traditional)
  • Minor aches and pains (traditional)
  • Antimicrobial (traditional)

White pepper comes from the same plant as black pepper and is mostly used as a kitchen spice. In normal food amounts it is generally safe for most people, but there is little solid human research supporting its use as a medicine. Talk with your pharmacist or doctor before using concentrated supplements, especially if you are pregnant, breastfeeding, or have a health condition.

Read the full White Pepper monograph & all interactions
Keep checking

Other Drugs & White Pepper

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

0Major
975Moderate
3Minor
1,851No known interaction
975 Moderate 3 Minor 1,851 No interaction
Moderate

975 interactions

Showing 60 of 975 moderate interactions — see all 975 on the White Pepper page.

Minor

3 interactions

No interaction 1,851 drugs checked — show the list

We also checked White Pepper against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,851 medications checked with no known interaction — see the full White Pepper list.

See the full White Pepper interactions page
See every supplement checked against Mephenytoin, 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
White Pepper monograph › Uses, safety, and every drug interaction in one place Mephenytoin supplement interactions › Every supplement checked against Mephenytoin, 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 White Pepper and Mephenytoin Together: Common Questions

Can you take White Pepper with Mephenytoin?
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 White Pepper and Mephenytoin 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 Mephenytoin and White Pepper?

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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.