Drug & supplement interaction

Peppermint + Flutamide

Flutamide brand names: Eulexin, Euflex.

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

Flutamide falls into 2 drug categories that Peppermint can interact with; the most serious is rated moderate. Theoretically, peppermint might increase the levels of CYP3A4 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Peppermint and Flutamide

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Peppermint interacts with whole categories of medication. Flutamide falls into 2 of those categories, so it can interact with Peppermint in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

1 of 2

Why this applies to Flutamide

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

Theoretically, peppermint might increase the levels of CYP3A4 substrates.
Clinical research in healthy volunteers shows that a single dose of peppermint oil 600 mg inhibits CYP3A4 enzymes and increases the AUC of felodipine, a CYP3A4 substrate. However, in vitro research suggests that peppermint oil only inhibits CYP3A4 at very high concentrations.
Severity Moderate Likelihood Possible Evidence B

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 prostate cancer treatment. Flutamide is processed by a liver enzyme called CYP3A4. Concentrated peppermint oil (think supplement capsules, not a cup of peppermint tea or a mint) can slow that enzyme down a bit. In theory, that could let a little more flutamide build up in your body, which might mean a higher chance of its usual side effects, like diarrhea, hot flashes, breast tenderness, nausea, or tiredness.

I want to be honest about the strength of this: it's mostly theoretical and based on one weaker study using another drug, and peppermint only seems to block this enzyme at fairly high amounts. Everyday food or tea is very unlikely to matter. If you're using peppermint oil capsules regularly, just give your pharmacist or oncologist a quick heads-up so they can keep an eye on things.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Dresser GK, Wacher V, Wong S, et al. Evaluation of peppermint oil and ascorbyl palmitate as inhibitors of cytochrome P4503A4 activity in vitro and in vivo. Clin Pharmacol Ther 2002;72:247-55. PubMed
  2. 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

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

2 of 2

Flutamide also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.

Theoretically, peppermint might increase the levels of CYP1A2 substrates.
In vitro and animal research shows that peppermint oil and peppermint leaf inhibit CYP1A2. However, in clinical research, peppermint tea did not significantly affect the metabolism of caffeine, a CYP1A2 substrate. It is possible that the 6-day duration of treatment may have been too short to identify a difference.
Severity Minor Likelihood Possible Evidence B

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 basic idea with peppermint and your flutamide. Flutamide is partly broken down by a liver enzyme called CYP1A2. In the test tube and in animals, concentrated peppermint oil seems to slow this enzyme down a little. If that happened in people, flutamide could build up slightly, which in theory might mean a bit more of its usual effects, like nausea, diarrhea, or liver-related issues (your doctor already watches your liver labs on this drug).

The good news is that this is mostly theoretical. In a real human study, peppermint tea didn't meaningfully change how a similar CYP1A2 drug was cleared. Everyday culinary amounts (tea, flavoring) are very unlikely to matter. If you're using concentrated peppermint oil capsules regularly, just give your pharmacist or oncologist a heads-up so they can keep an eye on things.

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
  2. Maliakal PP, Wanwimolruk S. Effect of herbal teas on hepatic drug metabolizing enzymes in rats. J Pharm Pharmacol 2001;53:1323-9. PubMed
  3. Begas E, Tsioutsiouliti A, Kouvaras E, et al. Effects of peppermint tea consumption on the activities of CYP1A2, CYP2A6, Xanthine Oxidase, N-acetyltranferase-2 and UDP-glucuronosyltransferases-1A1/1A6 in healthy volunteers. Food Chem Toxicol 2017;100:80-9 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

Peppermint Also Interacts With Other Medications

Peppermint has 732 moderate, 65 minor known drug interactions in our database — the Flutamide one above is among them. If you take anything else, check it against the full list below.

Moderate 732 Minor 65 No known interaction 2,033 (incl. Flutamide)
Taking anything else?

Check Another of Your Medications Against Peppermint

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

Everything else you take

See Every Supplement That Interacts With Flutamide

This page covers Peppermint only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Flutamide page lists 189 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 · 143 moderate · 43 minor.

From our pharmacist’s overview on the Flutamide page

“A man taking flutamide (Eulexin) to block testosterone during prostate cancer treatment cannot afford big swings in the drug's level, and most of the 189 supplements on this page are capable of causing exactly that. The bulk of them work through the liver enzyme CYP3A4, which breaks flutamide down.”

Reviewed by 2 · Jul 18, 2026

Open the Flutamide interaction page

One more smart check

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

We hold 1,980 real supplement products containing Peppermint, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Peppermint. Your product may carry other ingredients that interact with Flutamide too, on top of Peppermint — 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 Peppermint and Flutamide 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 Peppermint
Top 10%

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

29 days ago today
Medication Flutamide
Steady interest

#1,935 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 Peppermint

What is Peppermint?

Peppermint
  • Irritable bowel syndrome (IBS)
  • Indigestion and gas
  • Nausea
  • Tension headache (topical oil)
  • Colds and congestion
  • Freshening breath

Peppermint is a popular herb with the best evidence supporting enteric-coated peppermint oil for easing IBS symptoms. It is generally well tolerated for most adults, but it can cause heartburn and is not recommended in concentrated oil form for infants and young children. Check with your pharmacist or doctor before using it regularly, especially during pregnancy or breastfeeding.

Read the full Peppermint monograph & all interactions
Medication

About Flutamide

What Is Flutamide Used For?

Brand names: Eulexin, Euflex

Flutamide treats prostate cancer in men. Eulexin capsules are used with an LHRH-agonist (a type of hormone-lowering therapy) for locally confined Stage B2-C and Stage D2 metastatic (spread) prostate cancer.

For Stage B2-C disease, Eulexin and the goserelin acetate implant start eight weeks before radiation therapy and continue during it. For Stage D2 disease, Eulexin starts with the LHRH-agonist and continues until the cancer progresses.

See full Flutamide drug information
Keep checking

Other Drugs & Peppermint

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

0Major
732Moderate
65Minor
2,032No known interaction
732 Moderate 65 Minor 2,032 No interaction
Moderate

732 interactions

Showing 60 of 732 moderate interactions — see all 732 on the Peppermint page.

Minor

65 interactions

Showing 60 of 65 minor interactions — see all 65 on the Peppermint page.

No interaction 2,032 drugs checked — show the list

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

Showing the 60 most looked-up of 2,032 medications checked with no known interaction — see the full Peppermint list.

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

Can you take Peppermint with Flutamide?
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 2 interactions listed for Peppermint and Flutamide?
Flutamide belongs to more than one drug category, and Peppermint 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 Peppermint and Flutamide 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 Flutamide and Peppermint?

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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.