Drug & supplement interaction

Bitter Melon + Terfenadine

Terfenadine brand name: Seldane.

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

Bitter Melon has a moderate interaction with Terfenadine. Theoretically, bitter melon might increase levels of P-glycoprotein substrates.

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

Bitter Melon and Terfenadine

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

Moderate

P-GLYCOPROTEIN SUBSTRATES

Why this applies to Terfenadine

Terfenadine falls under P-GLYCOPROTEIN SUBSTRATES — the group Bitter Melon interacts with.

Theoretically, bitter melon might increase levels of P-glycoprotein substrates.
Bitter melon might inhibit the p-glycoprotein (P-gp) intestinal pump and increase intracellular levels of P-gp substrates. In vitro research in intestinal cells shows that 1-monopalmitin, a constituent of bitter melon, increases levels of daunomycin, a P-gp substrate. Additionally, drinking bitter melon juice has been associated with a case of acute pancreatitis in a patient who had been taking pazopanib, a P-gp substrate, for 8 years. Researchers theorize that inhibition of P-gp led to increased levels of pazopanib, resulting in pazopanib-induced pancreatitis.
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 gist for terfenadine (the old allergy drug Seldane): bitter melon may block a gut pump called P-glycoprotein that normally helps push drugs back out of your system. If that pump slows down, more terfenadine could get absorbed and build up in your blood.

That matters because terfenadine was actually pulled from the U.S. market for this very reason. When its levels climb too high, it can disturb the heart's rhythm (a dangerous change called QT prolongation). I'll be honest though, this interaction is only theoretical, based on lab and animal data, not human studies. Still, given terfenadine's known heart risks, please don't pair these without first checking with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Konishi T, Satsu H, Hatsugai Y, et al. Inhibitory effect of a bitter melon extract on the P-glycoprotein activity in intestinal Caco-2 cells. Br J Pharmacol. 2004;143(3):379-87. PubMed
  2. Unsal O, Sütcüoglu O, Yazici O. Dangerous interaction of bitter melon (Momordica charantia) with pazopanib: a case of acute pancreatitis. J Oncol Pharm Pract 2022;28(2):486-8.

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

Bitter Melon Also Interacts With Other Medications

Bitter Melon has 281 moderate known drug interactions in our database — the Terfenadine one above is one of them. If you take anything else, check it against the full list below.

Moderate 281 No known interaction 2,549 (incl. Terfenadine)
Taking anything else?

Check Another of Your Medications Against Bitter Melon

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

Everything else you take

See Every Supplement That Interacts With Terfenadine

This page covers Bitter Melon only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Terfenadine page lists 65 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 42 moderate · 15 minor.

From our pharmacist’s overview on the Terfenadine page

“Terfenadine (Seldane) is an older antihistamine with a well-known heart rhythm hazard, and its supplement list warrants genuine caution. Eight of the 65 interactions on file are rated major, and the biggest danger is additive strain on the heart's electrical timing: 13 ingredients can prolong the QT interval the way terfenadine itself…”

Reviewed by 2 · Jul 18, 2026

Open the Terfenadine interaction page

One more smart check

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

We hold 736 real supplement products containing Bitter Melon, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bitter Melon. Your product may carry other ingredients that interact with Terfenadine too, on top of Bitter Melon — 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 Bitter Melon and Terfenadine 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 Bitter Melon
Top 25%

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

29 days ago today
Medication Terfenadine
Steady interest

#2,669 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 Bitter Melon

What is Bitter Melon?

Bitter Melon
  • Blood sugar support
  • Diabetes
  • Digestive complaints
  • Antioxidant source
  • Skin conditions

Bitter melon is a tropical fruit eaten as food and used in traditional medicine, most often for blood sugar control. While some small studies hint it may modestly lower blood sugar, the evidence is limited and inconsistent, so it should not replace proven diabetes treatment. Talk with your pharmacist or doctor before using it, especially if you take diabetes medicines or are pregnant.

Read the full Bitter Melon monograph & all interactions
Keep checking

Other Drugs & Bitter Melon

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

0Major
281Moderate
0Minor
2,548No known interaction
281 Moderate 2,548 No interaction
Moderate

281 interactions

Showing 60 of 281 moderate interactions — see all 281 on the Bitter Melon page.

No interaction 2,548 drugs checked — show the list

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

Showing the 60 most looked-up of 2,548 medications checked with no known interaction — see the full Bitter Melon list.

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

Can you take Bitter Melon with Terfenadine?
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 Bitter Melon and Terfenadine 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 Terfenadine and Bitter Melon?

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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.