Drug & supplement interaction

Oregon Grape + Chlorpheniramine, Methscopolamine, Pseudoephedrine

Chlorpheniramine, Methscopolamine, Pseudoephedrine brand names: Mescolor, Rescon-Mx, Xiral.

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

Oregon Grape has a moderate interaction with Chlorpheniramine, Methscopolamine, Pseudoephedrine. Theoretically, Oregon grape might increase serum levels of drugs metabolized by CYP3A4.

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

Oregon Grape and Chlorpheniramine, Methscopolamine, Pseudoephedrine

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Chlorpheniramine, Methscopolamine, Pseudoephedrine

Chlorpheniramine, Methscopolamine, Pseudoephedrine falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Oregon Grape interacts with.

Theoretically, Oregon grape might increase serum levels of drugs metabolized by CYP3A4.
In vitro research and preliminary clinical evidence suggest that berberine, a constituent of Oregon grape, moderately inhibits cytochrome P450 3A4 (CYP3A4).
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 combination cold-and-allergy product contains an antihistamine (chlorpheniramine), a drying agent (methscopolamine), and a decongestant (pseudoephedrine). Berberine, the active compound in Oregon grape, may gently slow down a liver enzyme called CYP3A4 that helps clear chlorpheniramine. In theory, that could let a little more of it build up in your body, nudging up side effects like drowsiness, dry mouth, blurry vision, constipation, or trouble urinating.

Keep in mind this is a theoretical concern based mostly on lab work, not real cases, so it is unlikely to cause major problems for most people. Still, if you take Oregon grape as a concentrated supplement and notice extra sleepiness or dryness, mention it to your pharmacist or doctor before changing anything.

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
  2. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
  3. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
  4. Hermann, R. and von, Richter O. Clinical evidence of herbal drugs as perpetrators of pharmacokinetic drug interactions. Planta Med 2012;78(13):1458-1477. 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

Oregon Grape Also Interacts With Other Medications

Oregon Grape has 1,217 moderate known drug interactions in our database — the Chlorpheniramine, Methscopolamine, Pseudoephedrine one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,217 No known interaction 1,613 (incl. Chlorpheniramine, Methscopolamine, Pseudoephedrine)
Taking anything else?

Check Another of Your Medications Against Oregon Grape

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

Everything else you take

See Every Supplement That Interacts With Chlorpheniramine, Methscopolamine, Pseudoephedrine

This page covers Oregon Grape only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Chlorpheniramine, Methscopolamine, Pseudoephedrine page lists 231 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 10 major · 176 moderate · 45 minor.

From our pharmacist’s overview on the Chlorpheniramine, Methscopolamine, Pseudoephedrine page

“The three-drug combination of chlorpheniramine, methscopolamine, and pseudoephedrine (Mescolor, Rescon-Mx, Xiral) sits at the serious end of supplement interactions, with 231 ingredients on file and 10 rated major, and those ten are what to understand first. Most of the list splits into two problems.”

Reviewed by 2 · Jul 18, 2026

Open the Chlorpheniramine, Methscopolamine, Pseudoephedrine interaction page

One more smart check

Taking Oregon Grape as Part of a Dietary Supplement Product? Check It for Interactions

We hold 740 real supplement products containing Oregon Grape, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Oregon Grape. Your product may carry other ingredients that interact with Chlorpheniramine, Methscopolamine, Pseudoephedrine too, on top of Oregon Grape — 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 Oregon Grape and Chlorpheniramine, Methscopolamine, Pseudoephedrine 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 Oregon Grape
Top 25%

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

29 days ago today
Medication Chlorpheniramine, Methscopolamine, Pseudoephedrine
Top half

#1,221 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 Oregon Grape

What is Oregon Grape?

Oregon Grape
  • Psoriasis (topical)
  • Eczema and other skin conditions
  • Digestive upset
  • Mild skin infections
  • General 'detox' or tonic use

Oregon grape is a shrub whose root contains berberine and related compounds. The strongest (though still modest) evidence is for topical creams that may slightly ease psoriasis; evidence for other uses is limited. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full Oregon Grape monograph & all interactions
Keep checking

Other Drugs & Oregon Grape

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

0Major
1,217Moderate
0Minor
1,612No known interaction
1,217 Moderate 1,612 No interaction
Moderate

1,217 interactions

Showing 60 of 1,217 moderate interactions — see all 1,217 on the Oregon Grape page.

No interaction 1,612 drugs checked — show the list

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

Showing the 60 most looked-up of 1,612 medications checked with no known interaction — see the full Oregon Grape list.

See the full Oregon Grape interactions page
See every supplement checked against Chlorpheniramine, Methscopolamine, Pseudoephedrine, 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
Oregon Grape monograph › Uses, safety, and every drug interaction in one place Chlorpheniramine, Methscopolamine, Pseudoephedrine supplement interactions › Every supplement checked against Chlorpheniramine, Methscopolamine, Pseudoephedrine, 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 Oregon Grape and Chlorpheniramine, Methscopolamine, Pseudoephedrine Together: Common Questions

Can you take Oregon Grape with Chlorpheniramine, Methscopolamine, Pseudoephedrine?
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 Oregon Grape and Chlorpheniramine, Methscopolamine, Pseudoephedrine 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, Methscopolamine, Pseudoephedrine and Oregon Grape?

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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.