Drug & supplement interaction

Coleus + 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

Coleus has a moderate interaction with Dextromethorphan HBr, Guaifenesin. Theoretically, taking coleus might decrease 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

Coleus and Dextromethorphan HBr, Guaifenesin

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Dextromethorphan HBr, Guaifenesin

Dextromethorphan HBr, Guaifenesin falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Coleus interacts with.

Theoretically, taking coleus might decrease serum levels of drugs metabolized by CYP3A4.
In vitro research shows that coleus can activate the nuclear receptor, pregnane X receptor (PXR), which results in increased expression of CYP3A4. Although the clinical significance of this is not known, use caution when considering concomitant use of coleus and other drugs affected by these enzymes.
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 combo. Your cough and chest product mixes dextromethorphan (the cough suppressant) and guaifenesin (the mucus thinner). Dextromethorphan is partly cleared by a liver enzyme called CYP3A4. Lab studies hint that Coleus may speed up this enzyme, which in theory could clear dextromethorphan a little faster and make it slightly less effective at quieting your cough.

I want to be honest about the strength of this, though. It comes only from test-tube research, not real people, so the effect in everyday life is probably small or unnoticeable. Food-style amounts are unlikely to matter; concentrated forskolin supplements are the bigger question mark. If you notice your cough isn't easing up, or you have heart or blood pressure concerns, check in with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ding, X. and Staudinger, J. L. Induction of drug metabolism by forskolin: the role of the pregnane X receptor and the protein kinase a signal transduction pathway. J Pharmacol Exp Ther 2005;312(2):849-856. PubMed
  2. Staudinger, J. L., Ding, X., and Lichti, K. Pregnane X receptor and natural products: beyond drug-drug interactions. Expert.Opin Drug Metab Toxicol 2006;2(6):847-857. 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

Coleus Also Interacts With Other Medications

Coleus has 29 major, 885 moderate known drug interactions in our database — the Dextromethorphan HBr, Guaifenesin one above is one of them. If you take anything else, check it against the full list below.

Major 29 Moderate 885 No known interaction 1,916 (incl. Dextromethorphan HBr, Guaifenesin)
Taking anything else?

Check Another of Your Medications Against Coleus

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

Everything else you take

See Every Supplement That Interacts With Dextromethorphan HBr, Guaifenesin

This page covers Coleus 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 Coleus as Part of a Dietary Supplement Product? Check It for Interactions

We hold 803 real supplement products containing Coleus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Coleus. Your product may carry other ingredients that interact with Dextromethorphan HBr, Guaifenesin too, on top of Coleus — 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 Coleus 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 Coleus
Top 25%

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

29 days ago today
Medication Dextromethorphan HBr, Guaifenesin
Top half

#1,379 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 Coleus

What is Coleus?

Coleus
  • Weight management
  • Asthma and breathing
  • High blood pressure
  • Heart conditions
  • Glaucoma (eye pressure)
  • Exercise and body composition

Coleus is a plant from the mint family whose root contains a compound called forskolin, often marketed for weight loss, asthma, and heart health. While early lab and small human studies are interesting, solid proof that Coleus supplements help any of these conditions is limited. Talk to your pharmacist or doctor before using it, especially if you have heart problems or low blood pressure.

Read the full Coleus monograph & all interactions
Keep checking

Other Drugs & Coleus

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

29Major
885Moderate
0Minor
1,915No known interaction
29 Major 885 Moderate 1,915 No interaction
Major

29 interactions

Moderate

885 interactions

Showing 60 of 885 moderate interactions — see all 885 on the Coleus page.

No interaction 1,915 drugs checked — show the list

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

Showing the 60 most looked-up of 1,915 medications checked with no known interaction — see the full Coleus list.

See the full Coleus 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
Coleus 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 Coleus and Dextromethorphan HBr, Guaifenesin Together: Common Questions

Can you take Coleus 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.
How serious is the Coleus 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

Still Have a Question About Dextromethorphan HBr, Guaifenesin and Coleus?

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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.