Drug & supplement interaction

European Barberry + Chlorpheniramine

Chlorpheniramine brand names: Chlor-Trimeton, Teldrin.

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

Chlorpheniramine falls into 2 drug categories that European Barberry can interact with; the most serious is rated moderate. Theoretically, European barberry might increase the levels and clinical effects of CYP3A4 substrates.

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

European Barberry and Chlorpheniramine

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

Why Are There 2 Interactions?

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

1 of 2

Why this applies to Chlorpheniramine

Chlorpheniramine falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group European Barberry interacts with.

Theoretically, European barberry might increase the levels and clinical effects of CYP3A4 substrates.
There is very preliminary evidence suggesting that berberine, a constituent of European barberry, might inhibit the CYP3A4 enzyme. Theoretically, European barberry might have a similar effect.
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: your body uses an enzyme called CYP3A4 to help break down chlorpheniramine. Berberine, the main active compound in European barberry, may slow that enzyme down a bit. If clearance slows, a little more chlorpheniramine can linger in your system, which could nudge up its usual effects like drowsiness, dry mouth, blurry vision, or feeling foggy and groggy.

I want to be honest about the strength of this, though. It's theoretical, based on how berberine behaves in lab settings, not on real patient reports. For most folks it's unlikely to cause trouble, especially with occasional allergy use. Still, if you take barberry regularly or feel extra sleepy, check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wu X, Li Q, Xin H, Yu A, Zhong M. Effects of berberine on the blood concentration of cyclosporin A in renal transplanted recipients: clinical and pharmacokinetic study. Eur J Clin Pharmacol 2005;61:567-72. PubMed
Moderate

ANTICHOLINERGIC DRUGS

2 of 2

Chlorpheniramine also falls under ANTICHOLINERGIC DRUGS.

Theoretically, taking European barberry with anticholinergic drugs might cause additive effects.
In vitro evidence suggests that European barberry might have anticholinergic properties.
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 this pairing. Chlorpheniramine is an older antihistamine that already carries mild anticholinergic activity, which is why it can leave you feeling drowsy or dried out (think dry mouth, blurry vision, constipation, or trouble emptying your bladder). Some lab dish studies hint that European barberry may have anticholinergic-like effects of its own, so the worry is that the two could stack on top of each other and make those side effects a bit stronger.

I want to be honest about the evidence here: this is theoretical, based mostly on test-tube work, not real people. For most folks it's unlikely to be dramatic, but if you take both and notice more grogginess or dry mouth, mention it to your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Shamsa F, Ahmadiani A, Khosrokhavar R. Antihistaminic and anticholinergic activity of barberry fruit (Berberis vulgaris) in the guinea-pig ileum. J Ethnopharmacol 1999;64:161-6. 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 Chlorpheniramine one above is among them. If you take anything else, check it against the full list below.

Moderate 1,209 No known interaction 1,621 (incl. Chlorpheniramine)
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.

From our Q&A

Questions About European Barberry or Chlorpheniramine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers European Barberry or Chlorpheniramine, 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 Chlorpheniramine

This page covers European Barberry only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Chlorpheniramine page lists 198 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), Henbane (major), Lithium (major) and Scopolia (major).

By severity: 6 major · 149 moderate · 43 minor.

From our pharmacist’s overview on the Chlorpheniramine page

“An over-the-counter allergy pill sounds harmless, but chlorpheniramine (Chlor-Trimeton) has one of the longer supplement interaction lists I review, and it calls for real vigilance, with the major-rated entries the ones to understand first. Most of the list can shift how the body clears the drug: grapefruit can raise its levels while St.”

Reviewed by 2 · Jul 18, 2026

Open the Chlorpheniramine 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 Chlorpheniramine 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 Chlorpheniramine 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

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

29 days ago today
Medication Chlorpheniramine
Steady interest

#1,549 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
Medication

About Chlorpheniramine

What Is Chlorpheniramine Used For?

Brand names: Chlor-Trimeton, Teldrin

Chlorpheniramine is used to temporarily relieve common allergy symptoms caused by hay fever (allergic rhinitis) or other upper respiratory allergies. These include runny nose, sneezing, itchy or watery eyes, and itching of the nose or throat.

These uses are supported across multiple products — including tablets (such as Aller-chlor, Allergy, Allergy Relief, Allergy Time, Anti Allergy, and Chlorpheniramine Maleate), extended-release tablets (Allergy Relief and Chlorphen-12), the oral solution Ed Chlorped Jr, and the inhalers ClorRelief and ClorRelief KIDs.

See full Chlorpheniramine drug information
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 Chlorpheniramine, 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 Chlorpheniramine supplement interactions › Every supplement checked against Chlorpheniramine, ranked by severity Chlorpheniramine 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 European Barberry and Chlorpheniramine Together: Common Questions

Can you take European Barberry with Chlorpheniramine?
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 European Barberry and Chlorpheniramine?
Chlorpheniramine belongs to more than one drug category, and European Barberry 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 European Barberry and Chlorpheniramine 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 Chlorpheniramine 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.