Drug & supplement interaction

Resveratrol + Letrozole

Letrozole brand name: Femara.

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

Resveratrol has a moderate interaction with Letrozole. Theoretically, resveratrol might increase levels of drugs metabolized by CYP3A4.

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

Resveratrol and Letrozole

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Letrozole

Letrozole falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Resveratrol interacts with.

Theoretically, resveratrol might increase levels of drugs metabolized by CYP3A4.
In vitro research shows that resveratrol can inhibit the CYP3A4 enzyme. However, clinical research shows that taking resveratrol 3000 mg daily for 8 weeks does not necessitate dose adjustments to medications metabolized by CYP3A4.
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 resveratrol with letrozole (Femara). Letrozole is cleared from your body partly by a liver enzyme called CYP3A4. In test-tube studies, resveratrol can slow that enzyme down. If that happened in real life, letrozole could build up a bit, which in theory could nudge up side effects like hot flashes, joint or muscle aches, tiredness, or headache.

The reassuring part: this concern comes mostly from lab work, not from people. In an actual human study, resveratrol at a hefty 3000 mg a day for 8 weeks did not require dose changes for CYP3A4 medicines. So the real-world risk looks low. Letrozole is important cancer therapy, though, so loop in your oncologist or pharmacist before adding any supplement.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Piver B, Berthou F, Dreano Y, Lucas D. Inhibition of CYP3A, CYP1A and CYP2E1 activities by resveratrol and other non volatile red wine components. Toxicol Lett 2001;125:83-91. PubMed
  2. Yu, C., Shin, Y. G., Kosmeder, J. W., Pezzuto, J. M., and van Breemen, R. B. Liquid chromatography/tandem mass spectrometric determination of inhibition of human cytochrome P450 isozymes by resveratrol and resveratrol-3-sulfate. Rapid Commun.Mass Spectro PubMed
  3. Chachay VS, Macdonald GA, Martin JH, Whitehead JP, O'Moore-Sullivan TM, Lee P, Franklin M, Klein K, Taylor PJ, Ferguson M, Coombes JS, Thomas GP, Cowin GJ, Kirkpatrick CM, Prins JB, Hickman IJ. Resveratrol does not benefit patients with nonalcoholic fatty

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

Resveratrol Also Interacts With Other Medications

Resveratrol has 821 moderate known drug interactions in our database — the Letrozole one above is one of them. If you take anything else, check it against the full list below.

Moderate 821 No known interaction 2,009 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Resveratrol

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

From our Q&A

Questions About Resveratrol or Letrozole

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

This page covers Resveratrol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Letrozole page lists 142 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), 7-methoxyflavone (moderate) and Acacia Rigidula (moderate).

By severity: 3 major · 99 moderate · 40 minor.

From our pharmacist’s overview on the Letrozole page

“Letrozole (Femara) is prescribed to keep hormone-driven breast cancer from returning, so a supplement that shifts its blood level can quietly undercut treatment. Give this list of 142 ingredients genuine respect, and learn the three major entries first.”

Reviewed by 2 · Jul 18, 2026

Open the Letrozole interaction page

One more smart check

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

We hold 2,939 real supplement products containing Resveratrol, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Resveratrol. Your product may carry other ingredients that interact with Letrozole too, on top of Resveratrol — 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 Resveratrol and Letrozole 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 Resveratrol
Top 10%

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

29 days ago today
Medication Letrozole
Top 5%

#49 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 Resveratrol

What is Resveratrol?

Resveratrol
  • Heart and blood vessel health
  • Antioxidant support
  • Anti-aging
  • Blood sugar and metabolic support
  • General anti-inflammatory support

Resveratrol is a plant compound found in red grapes, berries, and peanuts that is popular for heart health, anti-aging, and antioxidant support. While lab and animal studies are promising, strong human evidence for most uses is still limited. It appears generally well tolerated in supplement doses, but talk with your pharmacist or doctor before starting it.

Read the full Resveratrol monograph & all interactions
Medication

About Letrozole

What Is Letrozole Used For?

Brand name: Femara

Letrozole (brand name Femara, or available as generic letrozole tablets) is used to treat breast cancer in postmenopausal women whose tumors are hormone receptor positive — meaning the cancer feeds on estrogen. It is used in several situations: as an adjuvant treatment (therapy given after primary treatment to reduce the risk of the cancer returning) for early breast cancer, and as extended adjuvant treatment for women who have already completed five years of tamoxifen therapy.

Femara and letrozole tablets are also used as first-line or second-line treatment for locally advanced or metastatic (spread to other areas) breast cancer in postmenopausal women, including cases where the cancer has progressed after other anti-estrogen therapy.

See full Letrozole drug information
Keep checking

Other Drugs & Resveratrol

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

0Major
821Moderate
0Minor
2,008No known interaction
821 Moderate 2,008 No interaction
Moderate

821 interactions

Showing 60 of 821 moderate interactions — see all 821 on the Resveratrol page.

No interaction 2,008 drugs checked — show the list

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

Showing the 60 most looked-up of 2,008 medications checked with no known interaction — see the full Resveratrol list.

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

Can you take Resveratrol with Letrozole?
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 Resveratrol and Letrozole 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 Letrozole and Resveratrol?

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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.