Drug & supplement interaction

Goldenseal + Metformin

Metformin brand names: Glucophage, Metformin.

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

Metformin falls into 2 drug categories that Goldenseal can interact with; the most serious is rated moderate. Theoretically, goldenseal might increase the risk of hypoglycemia when used with antidiabetes drugs.

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

Goldenseal and Metformin

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

Why Are There 2 Interactions?

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

Moderate

ANTIDIABETES DRUGS

1 of 2

Why this applies to Metformin

Metformin falls under ANTIDIABETES DRUGS — the group Goldenseal interacts with.

Theoretically, goldenseal might increase the risk of hypoglycemia when used with antidiabetes drugs.
Goldenseal contains berberine. Clinical research shows that berberine can lower blood glucose levels. However, this effect has not been reported with goldenseal.
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 with goldenseal and your metformin. Goldenseal contains a compound called berberine, and in studies berberine on its own can nudge blood sugar downward. Since metformin is already lowering your blood sugar, stacking the two together could in theory push it down a little too far, which we call hypoglycemia. With metformin that's not super common, but signs to watch for include shakiness, sweating, dizziness, a racing heart, or feeling unusually hungry or foggy.

I'll be honest, this is a theoretical concern. It's based on how berberine behaves, and low blood sugar hasn't actually been reported with goldenseal itself. So don't panic. If you'd like to use goldenseal, just check in with your pharmacist or doctor first and keep an eye on your home glucose readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Zhang Y, Li X, Zou D, et al. Treatment of type 2 diabetes and dyslipidemia with the natural plant alkaloid berberine. J Clin Endocrinol Metab 2008;93:2559-65. PubMed
  2. Yin, J., Xing, H., and Ye, J. Efficacy of berberine in patients with type 2 diabetes mellitus. Metabolism 2008;57(5):712-717. PubMed
  3. Zhang, H., Wei, J., Xue, R., Wu, J. D., Zhao, W., Wang, Z. Z., Wang, S. K., Zhou, Z. X., Song, D. Q., Wang, Y. M., Pan, H. N., Kong, W. J., and Jiang, J. D. Berberine lowers blood glucose in type 2 diabetes mellitus patients through increasing insulin re
  4. Wei, W., Zhao, H., Wang, A., Sui, M., Liang, K., Deng, H., Ma, Y., Zhang, Y., Zhang, H., and Guan, Y. A clinical study on the short-term effect of berberine in comparison to metformin on the metabolic characteristics of women with polycystic ovary syndro
Moderate

METFORMIN (Glucophage)

2 of 2
Theoretically, goldenseal might reduce blood levels of metformin.
In vitro research shows that goldenseal extract decreases the bioavailability of metformin, likely by interfering with transport, intestinal permeability, or other processes involved in metformin absorption. It is unclear which, if any, of metformin's transporters are inhibited by goldenseal. Goldenseal does not appear to alter the clearance or half-life of metformin.
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 with goldenseal and your metformin: in laboratory (test tube) studies, goldenseal seemed to lower the amount of metformin that gets absorbed from your gut into your bloodstream. Metformin isn't a prodrug, it works as-is, so less getting absorbed means less drug working. In plain terms, your metformin could become a little less effective at keeping your blood sugar in check.

I want to be honest about how soft this evidence is. This comes from lab research, not from real patients, so it's theoretical at this point. We don't even know which transporter is involved or whether food amounts versus concentrated supplement doses matter. Still, if you take goldenseal regularly, keep an eye on your blood sugar readings and chat with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Nguyen JT, Tian DD, Tanna RS, et al. Assessing transporter-mediated natural product-drug interactions via in vitro-in vivo extrapolation: clinical evaluation with a probe cocktail. Clin Pharmacol Ther 2021;109(5):1342-52.

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 Metformin one above is among them. If you take anything else, check it against the full list below.

Moderate 1,235 Minor 1 No known interaction 1,594 (incl. Metformin)
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.

From our Q&A

Questions About Goldenseal or Metformin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Goldenseal or Metformin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Metformin

This page covers Goldenseal only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin page lists 258 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate) and Agaricus Mushroom (moderate).

By severity: 2 major · 217 moderate · 39 minor.

From our pharmacist’s overview on the Metformin page

“Siberian cocklebur is the ingredient I most want anyone taking metformin (Glucophage) to know about. It has caused severe low blood sugar in people, documented in humans, and it should not be combined with any glucose-lowering medication.”

Reviewed by 2 · Jul 18, 2026

Open the Metformin 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 Metformin 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 Metformin 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%

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

29 days ago today
Medication Metformin
Top 5%

#32 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
Medication

About Metformin

What Is Metformin Used For?

Brand names: Glucophage, Metformin

Metformin — available as tablets, extended-release tablets, and an oral solution — is used to improve blood sugar (glucose) control in people with type 2 diabetes mellitus, always as part of a plan that includes diet and exercise.

Metformin hydrochloride tablets and the oral solution are approved for adults and children 10 years and older. Extended-release tablets (including Fortamet, Glumetza, and Metformin Hydrochloride Extended Release) are approved for adults only. Riomet (oral solution) is approved for adults and children 10 years and older.

See full Metformin drug information
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 Metformin, 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 Metformin supplement interactions › Every supplement checked against Metformin, ranked by severity Metformin 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 Goldenseal and Metformin Together: Common Questions

Can you take Goldenseal with Metformin?
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 Goldenseal and Metformin?
Metformin belongs to more than one drug category, and Goldenseal 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 Goldenseal and Metformin 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 Metformin 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.