Drug & supplement interaction

Goldenseal + Terfenadine

Terfenadine brand name: Seldane.

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

Goldenseal has a moderate interaction with Terfenadine. Theoretically, goldenseal might increase or decrease serum levels of P-glycoprotein (P-gp) substrates.

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

Goldenseal 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 Goldenseal interacts with.

Theoretically, goldenseal might increase or decrease serum levels of P-glycoprotein (P-gp) substrates.
There is conflicting evidence about the effect of goldenseal on P-gp. In vitro research suggests that berberine, a constituent of goldenseal, modestly inhibits P-gp efflux. Other evidence suggests that berberine induces P-gp. In healthy volunteers, goldenseal modestly increases peak levels of the P-gp substrate digoxin by about 14%. However, it does not seem to affect other pharmacokinetic parameters such as area under the curve (AUC). This suggests that goldenseal is not a potent inhibitor of P-gp-mediated drug efflux. Until more is known, goldenseal should be used cautiously with P-gp substrates.
Severity Moderate Likelihood Probable Evidence B

Interaction 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..

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

Here's the short version on mixing goldenseal with terfenadine (Seldane). Terfenadine is handled in part by a transporter called P-glycoprotein, which helps move the drug out of cells. Goldenseal's main compound, berberine, may nudge that transporter slightly, though the research is genuinely mixed (one study showed only a small ~14% bump in a similar drug, digoxin). So any real-world effect is likely modest, and this is mostly theoretical.

That said, terfenadine is a special case. It was actually pulled from the U.S. market years ago because, when its breakdown was slowed, it could build up and cause dangerous heart rhythm problems. So with this particular drug, I'd be cautious. Please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gurley BJ, Swain A, Barone GW, et al. Effect of goldenseal (Hydrastis canadensis) and kava kava (Piper methysticum) supplementation on digoxin pharmacokinetics in humans. Drug Metab Dispos 2007;35:240-5. 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

Goldenseal Also Interacts With Other Medications

Goldenseal has 1,235 moderate, 1 minor 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 1,235 Minor 1 No known interaction 1,594 (incl. Terfenadine)
Taking anything else?

Check Another of Your Medications Against Goldenseal

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

Everything else you take

See Every Supplement That Interacts With Terfenadine

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

We hold 1,726 real supplement products containing Goldenseal, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Goldenseal. Your product may carry other ingredients that interact with Terfenadine too, on top of Goldenseal — 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 Goldenseal 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 Goldenseal
Top 25%

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

29 days ago today
Medication Terfenadine
Steady interest

#2,710 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 Goldenseal

What is Goldenseal?

Goldenseal
  • Digestive upset and diarrhea
  • Colds and respiratory infections
  • Sore throat and mouth sores
  • Skin and eye irritation (topical/traditional)
  • Antimicrobial support

Goldenseal is a popular North American herb that contains berberine, a compound studied for antimicrobial effects. However, strong human evidence for its many traditional uses is largely lacking, and it should be avoided during pregnancy and breastfeeding. Talk to a pharmacist or doctor before using it.

Read the full Goldenseal monograph & all interactions
Keep checking

Other Drugs & Goldenseal

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

0Major
1,235Moderate
1Minor
1,593No known interaction
1,235 Moderate 1 Minor 1,593 No interaction
Moderate

1,235 interactions

Showing 60 of 1,235 moderate interactions — see all 1,235 on the Goldenseal page.

Minor

1 interaction

No interaction 1,593 drugs checked — show the list

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

Showing the 60 most looked-up of 1,593 medications checked with no known interaction — see the full Goldenseal list.

See the full Goldenseal 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
Goldenseal 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 Goldenseal and Terfenadine Together: Common Questions

Can you take Goldenseal 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 Goldenseal 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 Goldenseal?

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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.