Drug & supplement interaction

Gymnema + Lapatinib

Lapatinib brand name: Tykerb.

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

Gymnema has a minor interaction with Lapatinib. Theoretically, gymnema might increase levels of drugs metabolized by CYP3A4.

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

Gymnema and Lapatinib

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

Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Lapatinib

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

Theoretically, gymnema might increase levels of drugs metabolized by CYP3A4.
One in vitro study using rat liver microsomes shows that gymnema can modestly inhibit the CYP3A4 enzyme. However, other in vitro research using human liver microsomes shows that gymnema does not affect CYP3A4 activity. Animal research also shows that gymnema does not alter the function of CYP3A4. In one study in rats, oral administration of gymnema for 7 days did not alter the clearance of amlodipine, a CYP3A4 substrate.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the basic idea: your body relies on a liver enzyme called CYP3A4 to break down lapatinib (Tykerb). The thinking is that gymnema might slow that enzyme a little, which in theory could let lapatinib build up. Since lapatinib is the active drug itself (not a prodrug that needs switching on), higher levels would mean stronger effects, including a greater chance of side effects like diarrhea, nausea, rash, or, less commonly, liver or heart-rhythm concerns.

That said, the evidence here is very weak. This worry comes only from one test-tube study using rat liver, while human liver and animal studies showed no real effect on CYP3A4. So a true interaction is unlikely. Still, since lapatinib is a serious cancer medicine, please check with your oncologist or pharmacist before adding gymnema.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Rammohan B, Samit K, Chinmoy D, et al. Human cytochrome P450 enzyme modulation by gymnema sylvestre: a predictive safety evaluation by LC-MS/MS. Pharmacogn Mag. 2016 Jul;12(Suppl 4):S389-S394.
  2. Vaghela M, Sahu N, Kharkar P, Pandita N. In vivo pharmacokinetic interaction by ethanolic extract of gymnema sylvestre with CYP2C9 (tolbutamide), CYP3A4 (amlodipine) and CYP1A2 (phenacetin) in rats. Chem Biol Interact. 2017 Dec 25;278:141-151. PubMed
  3. Vaghela M, Iyer K, Pandita N. In vitro inhibitory effect of gymnema sylvestre extracts and total gymnemic acids fraction on select cytochrome P450 activities in rat liver microsomes. Eur J Drug Metab Pharmacokinet. 2017 Oct 10. 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

Gymnema Also Interacts With Other Medications

Gymnema has 347 moderate, 503 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 347 Minor 503 No known interaction 1,980 (incl. Lapatinib)
Taking anything else?

Check Another of Your Medications Against Gymnema

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

Everything else you take

See Every Supplement That Interacts With Lapatinib

This page covers Gymnema 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 Gymnema as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,084 real supplement products containing Gymnema, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Gymnema. Your product may carry other ingredients that interact with Lapatinib too, on top of Gymnema — 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 Gymnema 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 Gymnema
Top 25%

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

29 days ago today
Medication Lapatinib
Steady interest

#2,654 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 Gymnema

What is Gymnema?

Gymnema
  • Blood sugar support
  • Type 2 diabetes
  • Sugar cravings
  • Weight management
  • Cholesterol support

Gymnema is an Ayurvedic herb best known for possibly helping lower blood sugar and reducing the taste of sweetness on the tongue. Some early human studies are encouraging for blood sugar support, but the evidence is still limited and not strong enough to replace standard treatment. If you have diabetes or take other medicines, talk with your pharmacist or doctor before using it.

Read the full Gymnema 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 & Gymnema

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

0Major
347Moderate
503Minor
1,979No known interaction
347 Moderate 503 Minor 1,979 No interaction
Moderate

347 interactions

Showing 60 of 347 moderate interactions — see all 347 on the Gymnema page.

Minor

503 interactions

Showing 60 of 503 minor interactions — see all 503 on the Gymnema page.

No interaction 1,979 drugs checked — show the list

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

Showing the 60 most looked-up of 1,979 medications checked with no known interaction — see the full Gymnema list.

See the full Gymnema 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
Gymnema 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 Gymnema and Lapatinib Together: Common Questions

Can you take Gymnema with Lapatinib?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Gymnema and Lapatinib interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Lapatinib and Gymnema?

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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.