Drug & supplement interaction

Peppermint + Lapatinib

Lapatinib brand name: Tykerb.

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

Peppermint has a moderate interaction with Lapatinib. Theoretically, peppermint might increase the levels of CYP3A4 substrates.

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

Peppermint and Lapatinib

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Lapatinib

Lapatinib 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 lapatinib (Tykerb). Your liver clears this cancer drug using an enzyme called CYP3A4. Peppermint oil, in concentrated supplement form, may gently block that same enzyme. If lapatinib is cleared more slowly, its levels can creep up, which could mean more of its typical side effects, things like diarrhea, nausea, mouth sores, rash, or tiredness. With certain kinase inhibitors there's also concern about heart rhythm changes, so any added buildup is worth watching.

That said, this is mostly theoretical and based on weaker evidence. A little peppermint tea or flavoring almost certainly won't matter. Concentrated peppermint oil capsules are the real question. Since lapatinib is a serious medication, please run any peppermint supplement past your oncologist or pharmacist before starting it.

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

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 730 moderate, 65 minor known drug interactions in our database — the Lapatinib one above is one of them. If you take anything else, check it against the full list below.

Moderate 730 Minor 65 No known interaction 2,035 (incl. Lapatinib)
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 Lapatinib

This page covers Peppermint only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Lapatinib page lists 143 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 · 100 moderate · 40 minor.

From our pharmacist’s overview on the Lapatinib page

“Of the 143 supplements on file for lapatinib (Tykerb), nearly all press on the same point, the CYP3A4 enzyme that clears this HER2-targeted breast cancer drug. That deserves real caution, since lapatinib only works when its blood level stays in range.”

Reviewed by 2 · Jul 18, 2026

Open the Lapatinib 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 Lapatinib 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 Lapatinib 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%

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

29 days ago today
Medication Lapatinib
Steady interest

#2,744 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 Lapatinib

What Is Lapatinib Used For?

Brand name: Tykerb

Lapatinib tablets are used in combination with other medicines to treat certain types of advanced or metastatic breast cancer in patients whose tumors overexpress HER2 (a protein that drives tumor growth). It is not used alone.

Specifically, lapatinib tablets are used with capecitabine for HER2-positive advanced or metastatic breast cancer in patients who have already received prior therapy (including certain chemotherapy drugs and trastuzumab). Lapatinib tablets are also used with letrozole for postmenopausal women with hormone receptor-positive, HER2-positive metastatic breast cancer when hormonal therapy is appropriate. Tykerb is the brand name product with these same indicated uses.

See full Lapatinib 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
730Moderate
65Minor
2,034No known interaction
730 Moderate 65 Minor 2,034 No interaction
Moderate

730 interactions

Showing 60 of 730 moderate interactions — see all 730 on the Peppermint page.

Minor

65 interactions

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

No interaction 2,034 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 2,034 medications checked with no known interaction — see the full Peppermint list.

See the full Peppermint interactions page
See every supplement checked against Lapatinib, 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 Lapatinib supplement interactions › Every supplement checked against Lapatinib, ranked by severity Lapatinib 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 Lapatinib Together: Common Questions

Can you take Peppermint with Lapatinib?
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 Peppermint and Lapatinib 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 Lapatinib 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.