Drug & supplement interaction

European Barberry + Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine

Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine brand name: Colrex.

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

Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine falls into 3 drug categories that European Barberry can interact with; the most serious is rated moderate. Theoretically, concomitant use with drugs that have sedative properties may cause additive effects.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

European Barberry and Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

European Barberry interacts with whole categories of medication. Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine falls into 3 of those categories, so it can interact with European Barberry in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CNS DEPRESSANTS

1 of 3

Why this applies to Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine

Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine falls under CNS DEPRESSANTS — the group European Barberry interacts with.

Theoretically, concomitant use with drugs that have sedative properties may cause additive effects.
Animal research suggests that berberine, a constituent of European barberry, might have sedative effects. 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

Your Colrex combo already brings two ingredients that can make you drowsy: codeine (an opioid cough and pain reliever) and chlorpheniramine (a sedating antihistamine). On top of that, animal studies hint that the berberine in European barberry may have a mild calming or sedative effect of its own. So the concern here is simple addition: pairing them could leave you sleepier, foggier, or more lightheaded than the cold medicine alone.

I want to be honest that this is theoretical, based on lab and animal data rather than real patient reports, so it may not amount to much. Still, until you've talked it over with your pharmacist or doctor, go easy on driving or anything that needs you sharp, and don't add other sedating products on top.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Shanbhag, S. M., Kulkarni, H. J., and Gaitonde, B. B. Pharmacological actions of berberine on the central nervous system. Jpn.J Pharmacol 1970;20(4):482-487. PubMed
  2. Sabir M and Bhide NK. Study of some pharmacological actions of berberine. Ind J Physiol & Pharmac 1971;15(3):111-132.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

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

This Colrex combination has several ingredients, but the one to watch with European barberry is the codeine. Berberine, the main active compound in barberry, may gently block a liver enzyme called CYP3A4 that helps clear codeine and several other medicines. If that enzyme slows down, codeine could hang around a little longer and feel stronger. That can mean more drowsiness, dizziness, constipation, or slowed breathing, especially if you already feel sleepy from the chlorpheniramine in this product.

Keep in mind this is only a theoretical concern based on lab-type pharmacology, not solid human studies, so it may not happen at all. Still, since this combo already makes many people sleepy, it's worth a quick chat with your pharmacist or doctor before pairing it with a barberry or berberine supplement.

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

3 of 3

Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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 for Colrex, which is a combo product. One of its ingredients, chlorpheniramine, is an older antihistamine with built-in anticholinergic effects. That's the drying-out action behind side effects like dry mouth, blurry vision, constipation, trouble urinating, and feeling drowsy or foggy. Some lab studies hint that European barberry may have mild anticholinergic activity of its own, so in theory the two could stack on top of each other.

I want to be honest about the strength of this: it's a theoretical concern based on test-tube data, not real-world reports, so for most people it's unlikely to cause trouble. Still, if you notice extra dry mouth or grogginess while taking both, ease up and check with your pharmacist or doctor first.

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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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. Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine)
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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine

This page covers European Barberry only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine page lists 338 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Asarabacca (major), Beer (major) and Ephedra (major).

By severity: 18 major · 275 moderate · 45 minor.

From our pharmacist’s overview on the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine page

“Someone taking Colrex is usually fighting a miserable cold, and cold season is also when people reach for herbal sleep aids and energy boosters, which is exactly where this list bites hardest. Colrex combines acetaminophen, chlorpheniramine, codeine, and phenylephrine, and 18 of its 338 supplement interactions rate major, enough to war…”

Reviewed by 2 · Jul 18, 2026

Open the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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

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

29 days ago today
Medication Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine
Top half

#756 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine, 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine supplement interactions › Every supplement checked against Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine, 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine Together: Common Questions

Can you take European Barberry with Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine?
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 3 interactions listed for European Barberry and Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine?
Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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 Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine 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.