Drug & supplement interaction

Vitamin E + Fexofenadine

Fexofenadine brand name: Allegra.

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

Vitamin E has a moderate interaction with Fexofenadine. Theoretically, vitamin E might induce metabolism of CYP3A4, possibly reducing the levels CYP3A4 substrates.

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

Vitamin E and Fexofenadine

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Fexofenadine

Fexofenadine falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Vitamin E interacts with.

Theoretically, vitamin E might induce metabolism of CYP3A4, possibly reducing the levels CYP3A4 substrates.
Vitamin E appears to bind with the nuclear receptor, pregnane X receptor (PXR), which results in increased expression of CYP3A4. Although the clinical significance of this is not known, use caution when considering concomitant use of vitamin E and other drugs affected by these enzymes.
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 short version on pairing vitamin E with Allegra (fexofenadine): there's a theoretical concern that high-dose vitamin E could nudge up an enzyme called CYP3A4, which in turn might clear some medications a bit faster. If that happened with fexofenadine, you could in theory get slightly less allergy relief, meaning more sneezing, runny nose, or itching slipping through.

I want to be honest, though, this is based on lab reasoning, not real patient studies, so I wouldn't lose sleep over it. Fexofenadine is also mostly handled by transporters rather than heavy CYP3A4 breakdown, so the effect is likely small. Regular dietary amounts of vitamin E shouldn't matter at all. If you take high-dose supplements, just mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Landes N, Pfluger P, Kluth D, et al. Vitamin E activates gene expression via the pregnane X receptor. Biochem Pharmacol 2003;65:269-73. . PubMed
  2. Brigelius-Flohe R. Vitamin E and drug metabolism. Biochem Biophys Res Commun 2003;305:737-40. 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

Vitamin E Also Interacts With Other Medications

Vitamin E has 762 moderate, 1 minor known drug interactions in our database — the Fexofenadine one above is one of them. If you take anything else, check it against the full list below.

Moderate 762 Minor 1 No known interaction 2,067 (incl. Fexofenadine)
Taking anything else?

Check Another of Your Medications Against Vitamin E

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

From our Q&A

Questions About Vitamin E or Fexofenadine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Vitamin E or Fexofenadine, 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 Fexofenadine

This page covers Vitamin E only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fexofenadine page lists 154 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Apple (major), Grapefruit (major), St. John's Wort (major) and Sweet Orange (major).

By severity: 5 major · 111 moderate · 38 minor.

From our pharmacist’s overview on the Fexofenadine page

“An over-the-counter allergy pill sounds like the last place serious interactions would hide, but fexofenadine (Allegra) has 154 supplements and foods on file, and the five rated major deserve real attention before you combine it with much of anything else. Two of those five sit in most refrigerators.”

Reviewed by 2 · Jul 18, 2026

Open the Fexofenadine interaction page

One more smart check

Taking Vitamin E as Part of a Dietary Supplement Product? Check It for Interactions

We hold 22,182 real supplement products containing Vitamin E, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Vitamin E. Your product may carry other ingredients that interact with Fexofenadine too, on top of Vitamin E — 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 Vitamin E and Fexofenadine 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 Vitamin E
Top 10

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

29 days ago today
Medication Fexofenadine
Top 25%

#677 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 Vitamin E

What is Vitamin E?

Vitamin E
  • General antioxidant support
  • Skin and hair care
  • Heart health
  • Eye health (age-related conditions)
  • Immune support

Vitamin E is an essential fat-soluble vitamin and antioxidant that most people get in adequate amounts from a normal diet. Supplements can help correct a true deficiency, but high-dose vitamin E has not been clearly proven to prevent heart disease or cancer and may carry risks. Talk to your pharmacist or doctor before taking high doses.

Read the full Vitamin E monograph & all interactions
Medication

About Fexofenadine

What Is Fexofenadine Used For?

Brand name: Allegra

Fexofenadine temporarily relieves symptoms of hay fever (seasonal allergic rhinitis) and other upper respiratory allergies, including runny nose, sneezing, itchy or watery eyes, and itching of the nose or throat.

Several products — including Allegra Hives 24hr tablets — are specifically used to reduce hives (urticaria) and relieve the itching that comes with them. Keep in mind that fexofenadine will not prevent hives or stop an allergic skin reaction from happening in the first place.

See full Fexofenadine drug information
Keep checking

Other Drugs & Vitamin E

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

0Major
762Moderate
1Minor
2,066No known interaction
762 Moderate 1 Minor 2,066 No interaction
Moderate

762 interactions

Showing 60 of 762 moderate interactions — see all 762 on the Vitamin E page.

Minor

1 interaction

No interaction 2,066 drugs checked — show the list

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

Showing the 60 most looked-up of 2,066 medications checked with no known interaction — see the full Vitamin E list.

See the full Vitamin E interactions page
See every supplement checked against Fexofenadine, 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
Vitamin E monograph › Uses, safety, and every drug interaction in one place Fexofenadine supplement interactions › Every supplement checked against Fexofenadine, ranked by severity Fexofenadine 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 Vitamin E and Fexofenadine Together: Common Questions

Can you take Vitamin E with Fexofenadine?
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 Vitamin E and Fexofenadine 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 Fexofenadine and Vitamin E?

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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.