Drug & supplement interaction

European Barberry + Quinethazone

Quinethazone brand name: Hydromox.

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

European Barberry has a moderate interaction with Quinethazone. Theoretically, taking European barberry with antihypertensive drugs might increase the risk of hypotension.

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

European Barberry and Quinethazone

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Quinethazone

Quinethazone falls under ANTIHYPERTENSIVE DRUGS — the group European Barberry interacts with.

Theoretically, taking European barberry with antihypertensive drugs might increase the risk of hypotension.
Animal and human research suggests that European barberry extracts can have hypotensive effects.
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

Quinethazone (Hydromox) is a thiazide-type water pill that lowers blood pressure by helping your body get rid of extra salt and fluid. European barberry, mostly because of its berberine content, has shown some blood-pressure-lowering activity in animal and small human studies. So the concern here is simple addition: two things nudging your pressure down at the same time.

If you pair them, you could feel the lower-pressure side effects more strongly, like dizziness, lightheadedness, or feeling faint when you stand up. Keep in mind this warning is theoretical and based mainly on how these things work, not strong proof. Food amounts of barberry are unlikely to matter, but concentrated supplements are worth a quick chat with your pharmacist or doctor before starting.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fatehi M, Saleh TM, Fatehi-Hassanabad Z, et al. A pharmacological study on Berberis vulgaris fruit extract. J Ethnopharmacol 2005;102:46-52. PubMed
  2. Fatehi-Hassanabad, Z., Jafarzadeh, M., Tarhini, A., and Fatehi, M. The antihypertensive and vasodilator effects of aqueous extract from Berberis vulgaris fruit on hypertensive rats. Phytother Res 2005;19(3):222-225.
  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 Quinethazone 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. Quinethazone)
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 Quinethazone

This page covers European Barberry only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Quinethazone page lists 217 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Lithium (major) and Oleander (major).

By severity: 7 major · 186 moderate · 24 minor.

From our pharmacist’s overview on the Quinethazone page

“Quinethazone (Hydromox) is a thiazide-type water pill for high blood pressure and fluid buildup, and its supplement list calls for genuine care, starting with the seven entries rated major among the 217 on file. Most of the 186 moderate interactions come from herbs and foods that also lower blood pressure, so stacking them can drop you…”

Reviewed by 2 · Jul 18, 2026

Open the Quinethazone 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 Quinethazone 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 Quinethazone 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
Top half

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

29 days ago today
Medication Quinethazone
Steady interest

#1,726 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 Quinethazone, 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 Quinethazone supplement interactions › Every supplement checked against Quinethazone, 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 Quinethazone Together: Common Questions

Can you take European Barberry with Quinethazone?
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 Quinethazone 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 Quinethazone 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.