Drug & supplement interaction

European Barberry + Troglitazone

Troglitazone brand name: Rezulin.

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

European Barberry has a moderate interaction with Troglitazone. Theoretically, taking European barberry with antidiabetes drugs might increase the risk of hypoglycemia.

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

European Barberry and Troglitazone

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Troglitazone

Troglitazone falls under ANTIDIABETES DRUGS — the group European Barberry interacts with.

Theoretically, taking European barberry with antidiabetes drugs might increase the risk of hypoglycemia.
Preliminary clinical evidence suggests that European barberry juice reduces fasting glucose levels in patients with type 2 diabetes who are also taking antidiabetes drugs. Additionally, some animal studies show that berberine, a constituent of European barberry, has antiglycemic potential. Monitor blood glucose levels closely.
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 simple version: troglitazone (Rezulin) is a diabetes medicine that lowers your blood sugar. European barberry, mainly through its berberine content, also seems to nudge blood sugar downward. Put the two together and those effects can stack up, so your sugar could drop lower than you intend. That can show up as shakiness, sweating, a racing heart, dizziness, or feeling confused.

The evidence here is on the lighter side, coming from early studies and animal data, so this isn't a guaranteed problem. Still, it's worth respecting. If you're thinking about adding barberry, please loop in your pharmacist or doctor first and keep a closer eye on your glucose readings rather than starting or stopping anything on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Singh, J. and Kakkar, P. Antihyperglycemic and antioxidant effect of Berberis aristata root extract and its role in regulating carbohydrate metabolism in diabetic rats. J Ethnopharmacol. 5-4-2009;123(1):22-26. PubMed
  2. Gao, C. R., Zhang, J. Q., and Huang, Q. L. [Experimental study on berberin raised insulin sensitivity in insulin resistance rat models]. Zhongguo Zhong.Xi.Yi.Jie.He.Za Zhi. 1997;17(3):162-164. DOI
  3. Lazavi F, Mirmiran P, Sohrab G, Nikpayam O, Angoorani P, Hedayati M. The barberry juice effects on metabolic factors and oxidative stress in patients with type 2 diabetes: A randomized clinical trial. Complement Ther Clin Pract. 2018;31:170-174. 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

European Barberry Also Interacts With Other Medications

European Barberry has 1,209 moderate known drug interactions in our database — the Troglitazone one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,209 No known interaction 1,621 (incl. Troglitazone)
Taking anything else?

Check Another of Your Medications Against European Barberry

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

Everything else you take

See Every Supplement That Interacts With Troglitazone

This page covers European Barberry only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Troglitazone page lists 280 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Acai (moderate).

By severity: 4 major · 239 moderate · 37 minor.

From our pharmacist’s overview on the Troglitazone page

“Most people taking troglitazone (Rezulin) are managing type 2 diabetes, and this list reflects that. The great majority of the 280 flagged ingredients act on blood sugar, most lowering it and a few raising it, so pairing them with a diabetes medication makes glucose control less predictable and can tip it too low.”

Reviewed by 2 · Jul 18, 2026

Open the Troglitazone interaction page

One more smart check

Taking European Barberry as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2 real supplement products containing European Barberry, each one broken down to its full ingredient list — and combination products often carry several ingredients besides European Barberry. Your product may carry other ingredients that interact with Troglitazone too, on top of European Barberry — 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 European Barberry and Troglitazone 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 European Barberry
Steady interest

#1,148 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Troglitazone
Top 25%

#641 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 European Barberry

What is European Barberry?

European Barberry
  • Digestive upset
  • Antimicrobial support
  • Blood sugar support
  • Cholesterol and metabolic support
  • Skin conditions

European barberry is a shrub whose root, bark, and berries contain berberine, a bitter plant alkaloid that has been studied mostly in isolated form. Some early research on berberine is promising for blood sugar and cholesterol, but high-quality evidence for the whole barberry herb is limited. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full European Barberry monograph & all interactions
Keep checking

Other Drugs & European Barberry

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

0Major
1,209Moderate
0Minor
1,620No known interaction
1,209 Moderate 1,620 No interaction
Moderate

1,209 interactions

Showing 60 of 1,209 moderate interactions — see all 1,209 on the European Barberry page.

No interaction 1,620 drugs checked — show the list

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

Showing the 60 most looked-up of 1,620 medications checked with no known interaction — see the full European Barberry list.

See the full European Barberry interactions page
See every supplement checked against Troglitazone, 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
European Barberry monograph › Uses, safety, and every drug interaction in one place Troglitazone supplement interactions › Every supplement checked against Troglitazone, 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 European Barberry and Troglitazone Together: Common Questions

Can you take European Barberry with Troglitazone?
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 European Barberry and Troglitazone 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 Troglitazone and European Barberry?

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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.