Drug & supplement interaction

Berberine + Dextromethorphan HBr, Guaifenesin

Dextromethorphan HBr, Guaifenesin brand names: Vicks Formula 44E Cough & Chest Congestion Relief, Pediatric Vicks Formula 44e Cough & Chest Congesti.

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

Dextromethorphan HBr, Guaifenesin falls into 3 drug categories that Berberine can interact with; the most serious is rated moderate. Theoretically, berberine might increase serum levels of drugs metabolized by CYP2D6.

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

Berberine and Dextromethorphan HBr, Guaifenesin

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

Why Are There 3 Interactions?

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

Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

1 of 3

Why this applies to Dextromethorphan HBr, Guaifenesin

Dextromethorphan HBr, Guaifenesin falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Berberine interacts with.

Theoretically, berberine might increase serum levels of drugs metabolized by CYP2D6.
In vitro research and preliminary clinical evidence show that berberine can inhibit CYP2D6. Theoretically, use of berberine with drugs metabolized by CYP2D6 might increase drug levels and increase the risk of adverse effects.
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 for your cough syrup. The dextromethorphan part is cleared from your body by a liver enzyme called CYP2D6. Berberine can slow that enzyme down, so the dextromethorphan may hang around longer and build up a bit. That can mean more of its usual effects, like drowsiness, dizziness, or feeling a little foggy or lightheaded. The guaifenesin part isn't really affected, so no worries there.

Honestly, this is mostly a theoretical concern based on lab work and some early studies, and a few doses of cough syrup is short-term. Still, if you take berberine regularly, it's worth a quick chat with your pharmacist before reaching for this medicine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chatterjee P, Franklin MR. Human cytochrome p450 inhibition and metabolic-intermediate complex formation by goldenseal extract and its methylenedioxyphenyl components. Drug Metab Dispos 2003;31:1391-7. PubMed
  2. 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
  3. 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
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Dextromethorphan HBr, Guaifenesin also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, berberine might increase serum levels of drugs metabolized by CYP3A4.
In vitro research and preliminary clinical research show that berberine moderately inhibits CYP3A4. Theoretically, use of berberine with drugs metabolized by CYP3A4 might increase drug levels and increase the risk of adverse effects.
Severity Moderate Likelihood Possible Evidence A

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 for your cough syrup. Berberine can mildly slow down a liver enzyme called CYP3A4, which is one of the pathways that helps clear dextromethorphan from your body. If that pathway slows, a little more dextromethorphan can hang around, which might mean more of its usual effects like drowsiness, dizziness, or feeling a bit foggy. The guaifenesin part isn't really involved here.

Honestly, this is mostly a theoretical concern, and an occasional dose of cough medicine is unlikely to cause trouble. Still, if you take berberine regularly and reach for this product, it's worth a quick chat with your pharmacist, especially if you notice extra sleepiness.

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
Moderate

DEXTROMETHORPHAN (Robitussin DM, others)

3 of 3
Theoretically, berberine may increase serum levels of dextromethorphan.
Preliminary clinical research shows that berberine can inhibit cytochrome P450 2D6 (CYP2D6) activity and reduce the metabolism of dextromethorphan. This may increase the effects and side effects of dextromethorphan.
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. Your body relies on an enzyme called CYP2D6 to clear the dextromethorphan (the cough-suppressing part of this combo). Berberine appears to slow that enzyme down, so the dextromethorphan can hang around longer and build up a bit. The guaifenesin (the mucus-thinning part) isn't really involved here. The end result is that the cough medicine's effects, and its side effects, may feel stronger than usual.

In real life that could mean more drowsiness, dizziness, nausea, or feeling foggy. This is mostly based on early, lower-quality research, so it's a maybe, not a sure thing. A few doses of cough syrup probably won't cause drama, but if you take berberine regularly, just give your pharmacist or doctor a heads-up before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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

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

Berberine Also Interacts With Other Medications

Berberine has 1 major, 1,158 moderate known drug interactions in our database — the Dextromethorphan HBr, Guaifenesin one above is among them. If you take anything else, check it against the full list below.

Major 1 Moderate 1,158 No known interaction 1,671 (incl. Dextromethorphan HBr, Guaifenesin)
Taking anything else?

Check Another of Your Medications Against Berberine

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

From our Q&A

Questions About Berberine or Dextromethorphan HBr, Guaifenesin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Berberine or Dextromethorphan HBr, Guaifenesin, 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 Dextromethorphan HBr, Guaifenesin

This page covers Berberine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dextromethorphan HBr, Guaifenesin page lists 171 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), Lithium (major), St. John's Wort (major) and 1,3-dmaa (moderate).

By severity: 4 major · 125 moderate · 42 minor.

From our pharmacist’s overview on the Dextromethorphan HBr, Guaifenesin page

“A bad cough tends to hit when supplements are already on the counter, and anyone reaching for Vicks Formula 44E (dextromethorphan HBr and guaifenesin) should treat this list with real care, since 4 of its 171 entries carry a major rating. Two themes dominate.”

Reviewed by 2 · Jul 18, 2026

Open the Dextromethorphan HBr, Guaifenesin interaction page

One more smart check

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

We hold 908 real supplement products containing Berberine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Berberine. Your product may carry other ingredients that interact with Dextromethorphan HBr, Guaifenesin too, on top of Berberine — 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 Berberine and Dextromethorphan HBr, Guaifenesin 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 Berberine
Top 10%

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

29 days ago today
Medication Dextromethorphan HBr, Guaifenesin
Top half

#1,394 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 Berberine

What is Berberine?

Berberine
  • Blood sugar control
  • High cholesterol
  • Heart and metabolic health
  • Digestive upset
  • Antimicrobial support
  • Weight management

Berberine is a yellow plant compound that has shown promise for lowering blood sugar and cholesterol in some studies, but the quality of research varies and it is not a replacement for prescribed medicine. It can cause stomach upset and should be avoided during pregnancy and breastfeeding. Always check with your pharmacist or doctor before starting it, especially if you take other medications.

Read the full Berberine monograph & all interactions
Keep checking

Other Drugs & Berberine

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

1Major
1,158Moderate
0Minor
1,670No known interaction
1 Major 1,158 Moderate 1,670 No interaction
Major

1 interaction

Moderate

1,158 interactions

Showing 60 of 1,158 moderate interactions — see all 1,158 on the Berberine page.

No interaction 1,670 drugs checked — show the list

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

Showing the 60 most looked-up of 1,670 medications checked with no known interaction — see the full Berberine list.

See the full Berberine interactions page
See every supplement checked against Dextromethorphan HBr, Guaifenesin, 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
Berberine monograph › Uses, safety, and every drug interaction in one place Dextromethorphan HBr, Guaifenesin supplement interactions › Every supplement checked against Dextromethorphan HBr, Guaifenesin, 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 Berberine and Dextromethorphan HBr, Guaifenesin Together: Common Questions

Can you take Berberine with Dextromethorphan HBr, Guaifenesin?
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 Berberine and Dextromethorphan HBr, Guaifenesin?
Dextromethorphan HBr, Guaifenesin belongs to more than one drug category, and Berberine 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 Berberine and Dextromethorphan HBr, Guaifenesin 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

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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.