Drug & supplement interaction

Higenamine + Dextromethorphan HBr, Phenylephrine HCl

Dextromethorphan HBr, Phenylephrine HCl brand name: Vicks Formula 44D Cough & Head Congestion Relief.

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

Dextromethorphan HBr, Phenylephrine HCl falls into 3 drug categories that Higenamine can interact with; the most serious is rated moderate. Theoretically, higenamine might increase the levels and clinical effects of drugs metabolized by CYP2D6.

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

Higenamine and Dextromethorphan HBr, Phenylephrine HCl

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

Why Are There 3 Interactions?

Higenamine interacts with whole categories of medication. Dextromethorphan HBr, Phenylephrine HCl falls into 3 of those categories, so it can interact with Higenamine 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, Phenylephrine HCl

Dextromethorphan HBr, Phenylephrine HCl falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Higenamine interacts with.

Theoretically, higenamine might increase the levels and clinical effects of drugs metabolized by CYP2D6.
In vitro research shows that higenamine inhibits CYP2D6 enzymes. However, this effect has not been reported in humans.
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 liver uses an enzyme called CYP2D6 to clear dextromethorphan, the cough-suppressing part of Vicks Formula 44D. In lab (test tube) studies, higenamine appears to slow that enzyme down. If that happened in your body, dextromethorphan could build up a bit, which might mean more drowsiness, dizziness, or a foggy, spaced-out feeling than usual.

Honestly though, this has only been seen in lab studies, not in real people, so I wouldn't lose sleep over it. My bigger concern is that higenamine itself acts like adrenaline and can raise heart rate and blood pressure, and the phenylephrine here is also a stimulant decongestant. Stacking them could leave you jittery or your heart racing. Please run this past your pharmacist before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu Y, Santillo MF. Cytochrome P450 2D6 and 3A4 enzyme inhibition by amine stimulants in dietary supplements. Drug Test Anal. 2016;8(3-4):307-10. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

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

Theoretically, higenamine might increase the levels and clinical effects drugs metabolized by CYP3A4.
In vitro research shows that higenamine inhibits CYP3A4 enzymes by 21%. However, this effect has not been reported in humans.
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 cold product contains dextromethorphan, which the liver partly clears through an enzyme called CYP3A4. In a test-tube study, higenamine slowed that enzyme by about 21 percent. If that happened in a real person, dextromethorphan could build up a little, which might mean more drowsiness, dizziness, or feeling foggy. Keep in mind this is only lab data and has never actually been shown in people, so I wouldn't lose sleep over it.

My bigger concern is overlap, not metabolism. Higenamine acts like adrenaline and can raise heart rate and blood pressure, and so can the phenylephrine decongestant here. Together they could leave you jittery or push your blood pressure up. Please check with your pharmacist before pairing them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu Y, Santillo MF. Cytochrome P450 2D6 and 3A4 enzyme inhibition by amine stimulants in dietary supplements. Drug Test Anal. 2016;8(3-4):307-10. PubMed
Moderate

STIMULANT DRUGS

3 of 3

Dextromethorphan HBr, Phenylephrine HCl also falls under STIMULANT DRUGS.

Theoretically, higenamine might increase the risk of cardiovascular toxicity when taken with stimulant drugs.
Higenamine has stimulant effects due to agonist activity at beta2-adrenoreceptors. In cardiac muscle, higenamine appears to have a positive inotropic effect and increase heart rate. However, it does not appear to increase blood pressure.
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

The piece in this cough and congestion product that matters here is the phenylephrine. It's a decongestant that works by tightening blood vessels, which can nudge up blood pressure and put a little extra work on your heart. Higenamine is also a stimulant that can speed up heart rate. Stacking the two together could, in theory, add up to more strain on your cardiovascular system, things like a racing or pounding heartbeat, jitteriness, or feeling wired.

To be honest, this concern is theoretical, based on how these substances act rather than real-world reports, so I don't want to overstate it. Still, since higenamine products are often mislabeled and unpredictable, I'd skip combining them and check with your pharmacist, especially if you have any heart or blood pressure history.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wagner H, Reiter M, Ferstl W. New drugs with cardiotonic activity. Part 1. Chemistry and pharmacology of the cardiotonic active principle of Annona squamosa L. Planta Med 1980;40:77-85.
  2. Park CW, Chang KC, Lim JK. Effects of higenamine on isolated heart adrenoceptor of rabbit. Arch Int Pharmacodyn Ther 1984;267:279-88.
  3. Liu WH, Zhou YP, Zeng GY. Effects of dl-demethylcoclaurine on experimental heart failure. Acta Pharm Sinica 1988;23:81-5.
  4. Zhang Z, Liu X, Tao Z, et al. Effects of higeramine on hemodynamics and its tolerability and safety, an experimental study. Zhonghua Yi Xue Za Zhi 2002;82:352-5.

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

Higenamine Also Interacts With Other Medications

Higenamine has 890 moderate known drug interactions in our database — the Dextromethorphan HBr, Phenylephrine HCl one above is among them. If you take anything else, check it against the full list below.

Moderate 890 No known interaction 1,940 (incl. Dextromethorphan HBr, Phenylephrine HCl)
Taking anything else?

Check Another of Your Medications Against Higenamine

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

Everything else you take

See Every Supplement That Interacts With Dextromethorphan HBr, Phenylephrine HCl

This page covers Higenamine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dextromethorphan HBr, Phenylephrine HCl page lists 197 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), Lithium (major) and Peyote (major).

By severity: 8 major · 148 moderate · 41 minor.

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

“The supplement interactions with Dextromethorphan HBr and Phenylephrine HCl (Vicks Formula 44D) deserve real respect, and the small cluster of major-rated ones should be understood before you reach for the bottle. Phenylephrine is a stimulant-type decongestant, so anything with caffeine (coffee, tea, cola nut) or ephedrine-like herbs s…”

Reviewed by 2 · Jul 18, 2026

Open the Dextromethorphan HBr, Phenylephrine HCl interaction page

One more smart check

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

We hold 154 real supplement products containing Higenamine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Higenamine. Your product may carry other ingredients that interact with Dextromethorphan HBr, Phenylephrine HCl too, on top of Higenamine — 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 Higenamine and Dextromethorphan HBr, Phenylephrine HCl 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 Higenamine
Top half

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

29 days ago today
Medication Dextromethorphan HBr, Phenylephrine HCl
Steady interest

#2,697 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 Higenamine

What is Higenamine?

  • Weight loss and fat burning
  • Pre-workout energy and performance
  • Appetite suppression
  • Athletic stimulant
  • Traditional medicine remedies

Higenamine is a plant-based stimulant compound added to many weight-loss and pre-workout supplements, but there is very little human evidence that it works and real concerns about heart and blood pressure effects. It is banned in sports by the World Anti-Doping Agency (WADA), and product labels often list inaccurate amounts, so most people should approach it with caution and talk to a pharmacist or doctor first.

Read the full Higenamine monograph & all interactions
Keep checking

Other Drugs & Higenamine

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

0Major
890Moderate
0Minor
1,939No known interaction
890 Moderate 1,939 No interaction
Moderate

890 interactions

Showing 60 of 890 moderate interactions — see all 890 on the Higenamine page.

No interaction 1,939 drugs checked — show the list

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

Showing the 60 most looked-up of 1,939 medications checked with no known interaction — see the full Higenamine list.

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

Can you take Higenamine with Dextromethorphan HBr, Phenylephrine HCl?
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 Higenamine and Dextromethorphan HBr, Phenylephrine HCl?
Dextromethorphan HBr, Phenylephrine HCl belongs to more than one drug category, and Higenamine 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 Higenamine and Dextromethorphan HBr, Phenylephrine HCl 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.