Medication interaction hub

What Supplements Interact with Dextromethorphan HBr, Phenylephrine HCl?

Dextromethorphan HBr, Phenylephrine HCl brand name: Vicks Formula 44D Cough & Head Congestion Relief. Every interaction below applies to the brands too.

197 Interactions 8 Major 148 Moderate 41 Minor
Curated & coded by · Clinical Pharmacist · Updated September 29, 2026

Drug–supplement interaction data sourced from Natural Medicines Pro, the licensed clinical database from TRC Healthcare / Therapeutic Research, with additional analysis by the HelloPharmacist Pharmacist Team. Our sources · Editorial policy

What is this page for?

One answer, for one medication: what supplements and herbal products interact with Dextromethorphan HBr, Phenylephrine HCl? Every vitamin, herb, and supplement ingredient we’ve checked against it is on this page, ranked by severity, each linking to the full report for that exact pair.

This page covers supplement interactions only — to check Dextromethorphan HBr, Phenylephrine HCl against your other medications, use the drug–drug interaction checker. Educational information from our licensed clinical databases, not medical advice. Our editorial policy

HelloPharmacist Bottom Line
Our Pharmacist Explains
What is this? The interaction data in the HelloPharmacist supplement database is licensed from Natural Medicines Pro by TRC Healthcare (Therapeutic Research). HelloPharmacist pharmacists often add our own analysis and context on top of that licensed data — such as this Bottom Line summary and the notes on individual interaction pages — and any such commentary is noted as ours.

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 stacks extra strain on your heart and blood pressure. Dextromethorphan touches serotonin, so serotonergic supplements can nudge you toward serotonin syndrome. And the biggest single group changes how your liver processes the medicine, with grapefruit raising drug levels and St. John's wort lowering them.

A few entries also blunt absorption outright, activated charcoal among them, so oral doses need spacing well apart. The list runs to 197 ingredients in all, though only 8 rate major, with 148 moderate and 41 minor behind them.

— , Clinical Pharmacist · July 18, 2026

Major 8 Moderate 148 Minor 41 No known interaction 1,255

This box checks one ingredient at a time (like turmeric or magnesium). Taking a supplement product with a whole label of ingredients? Search the product instead — we check every ingredient on it ↓

Most Viewed Ingredient Interactions

Dextromethorphan HBr, Phenylephrine HCl: Top Interactions at a Glance

The Dextromethorphan HBr, Phenylephrine HCl supplement & herbal interactions people checked most in the last 24 hours, colored by severity. Tap any ingredient to open the full report for that pair.

Showing the 12 highest-ranked of 197 interacting ingredients — plus 1,255 more checked with no known interaction. See the complete ranked list.

Start here

The Most-Checked Dextromethorphan HBr, Phenylephrine HCl Combinations Today

The Dextromethorphan HBr, Phenylephrine HCl + supplement pages people viewed most in the last 24 hours (resets at midnight). Open any card for the full report.

Moderate Likelihood Probable Caffeine + Dextromethorphan HBr, Phenylephrine HCli

Theoretically, concomitant use might increase stimulant adverse effects.

Read the full interaction Minor Likelihood Possible Rhodiola + Dextromethorphan HBr, Phenylephrine HCli

Theoretically, rhodiola might increase levels of drugs metabolized by CYP3A4.

Read the full interaction Moderate Likelihood Possible Boswellia Serrata + Dextromethorphan HBr, Phenylephrine HCli

Theoretically, Boswellia serrata might increase the levels of CYP2D6 substrates.

Read the full interaction Major Likelihood Probable Peyote + Dextromethorphan HBr, Phenylephrine HCli

Concomitant use of peyote with stimulant drugs may increase the risk of adverse CNS effects.

Read the full interaction Major Likelihood Likely Grapefruit + Dextromethorphan HBr, Phenylephrine HCli

Grapefruit juice can increase levels of drugs metabolized by CYP3A4.

Read the full interaction Major Likelihood Probable Activated Charcoal + Dextromethorphan HBr, Phenylephrine HCli

Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.

Read the full interaction
The complete list

Every Supplement Checked Against Dextromethorphan HBr, Phenylephrine HCl

All 1,452 ingredients in our database, ranked by severity — 197 with a Dextromethorphan HBr, Phenylephrine HCl interaction on file and 1,255 with none found. Filter by severity or search any ingredient; hover the for what each ingredient is.

Looking for an interaction with a specific supplement product? Search products instead ↓

Straight answers

Can You Take It With Dextromethorphan HBr, Phenylephrine HCl?

One-line answers, one card per combination — scroll through today’s 20 and tap any card for the full report. A different set rotates in daily until every combination has had its turn.

Can you take Caffeine with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, concomitant use might increase stimulant adverse effects.

Full Caffeine + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Rhodiola with Dextromethorphan HBr, Phenylephrine HCl?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, rhodiola might increase levels of drugs metabolized by CYP3A4.

Full Rhodiola + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Boswellia Serrata with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, Boswellia serrata might increase the levels of CYP2D6 substrates.

Full Boswellia Serrata + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Peyote with Dextromethorphan HBr, Phenylephrine HCl?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Concomitant use of peyote with stimulant drugs may increase the risk of adverse CNS effects.

Full Peyote + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Greater Celandine with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Research in vitro shows that chelidonine, a constituent of greater celandine, inhibits cytochrome P450 2D6 (CYP2D6) enzyme activity.

Full Greater Celandine + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Griffonia Simplicifolia with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, taking Griffonia simplicifolia seed extract with dextromethorphan might increase the risk of serotonergic adverse effects, su...

Full Griffonia Simplicifolia + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Guar Gum with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Guar gum might reduce the absorption of some oral drugs, potentially decreasing their effectiveness.

Full Guar Gum + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Guarana with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, concomitant use might increase stimulant adverse effects.

Full Guarana + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Gum Arabic with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, gum arabic can alter the absorption of oral drugs due to its fiber content.

Full Gum Arabic + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Hawaiian Baby Woodrose with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, concomitant use may increase the risk for serotonergic adverse effects.

Full Hawaiian Baby Woodrose + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Higenamine with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, higenamine might increase the levels and clinical effects of drugs metabolized by CYP2D6.

Full Higenamine + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Hordenine with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Hordenine is structurally similar to N-methyltyramine and synephrine, constituents in bitter orange known to have stimulant properties.

Full Hordenine + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Horny Goat Weed with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, horny goat weed might increase the effects and side effects of CYP3A4 substrates.

Full Horny Goat Weed + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Hu Zhang with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, hu zhang might increase levels of drugs metabolized by CYP3A4.

Full Hu Zhang + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Iboga with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, taking iboga with serotonergic drugs might increase levels of serotonin, resulting in additive effects with serotonergic drug...

Full Iboga + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Indian Long Pepper with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, Indian long pepper might increase the effects and adverse effects of CYP3A4 substrates.

Full Indian Long Pepper + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Indian Snakeroot with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, Indian snakeroot might inhibit CYP2D6 enzymes and reduce the metabolism of CYP2D6 substrates.

Full Indian Snakeroot + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Isopropylnorsynephrine with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, taking isopropylnorsynephrine with stimulant drugs might have additive effects and increase the risk of adverse cardiovascula...

Full Isopropylnorsynephrine + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Job's Tears with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Animal research suggests that Job's tears might enhance absorption of dextromethorphan in the small intestine.

Full Job's Tears + Dextromethorphan HBr, Phenylephrine HCl answer

Can you take Khat with Dextromethorphan HBr, Phenylephrine HCl?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Cathinone, a constituent of khat, appears to have sympathomimetic effects and can increase blood pressure and heart rate.

Full Khat + Dextromethorphan HBr, Phenylephrine HCl answer
Read the list like a pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each entry links to a full report with the clinical detail, likelihood, evidence level, and citations for that exact combination.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

How Does Our Interaction Checker Work?

Behind every verdict on this page is a category system. Our source database doesn’t document supplement interactions drug-by-drug — it documents them against groups of medications that behave the same way (for example, “drugs processed by the CYP3A4 liver enzyme” or “blood-thinning medications”).

So the check works in three steps: (1) Dextromethorphan HBr, Phenylephrine HCl is classified into the pharmacology categories it belongs to, (2) every supplement interaction documented against any of those categories is inherited by Dextromethorphan HBr, Phenylephrine HCl, and (3) each ingredient keeps its own severity, likelihood, and evidence grades from the underlying record. That’s why one supplement can carry several records for one drug — it may interact through more than one category.

Dextromethorphan HBr, Phenylephrine HCl sits in 8 interaction categories. Open any one to see what the group means:

Cytochrome P450 3A4 (Cyp3A4) Substrates 121 ingredients

A drug-metabolism group: these medications are processed by the named liver enzyme (a cytochrome P450). Supplements that speed this enzyme up or slow it down can lower or raise the medication's levels in your body.

121 of the supplement ingredients on this page reach Dextromethorphan HBr, Phenylephrine HCl through this category.

Cytochrome P450 2D6 (Cyp2D6) Substrates 60 ingredients

A drug-metabolism group: these medications are processed by the named liver enzyme (a cytochrome P450). Supplements that speed this enzyme up or slow it down can lower or raise the medication's levels in your body.

60 of the supplement ingredients on this page reach Dextromethorphan HBr, Phenylephrine HCl through this category.

Stimulant Drugs 44 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

44 of the supplement ingredients on this page reach Dextromethorphan HBr, Phenylephrine HCl through this category.

Serotonergic Drugs 20 ingredients

Medications that raise serotonin activity. Combining them with serotonin-active supplements can, in rare cases, push serotonin too high.

20 of the supplement ingredients on this page reach Dextromethorphan HBr, Phenylephrine HCl through this category.

Oral Drugs 17 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

17 of the supplement ingredients on this page reach Dextromethorphan HBr, Phenylephrine HCl through this category.

Dextromethorphan (Robitussin Dm, Others) 9 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

9 of the supplement ingredients on this page reach Dextromethorphan HBr, Phenylephrine HCl through this category.

Alpha-Adrenergic Agonists 1 ingredient

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

1 of the supplement ingredient on this page reaches Dextromethorphan HBr, Phenylephrine HCl through this category.

Serotonergic Drugs 1 ingredient

Medications that raise serotonin activity. Combining them with serotonin-active supplements can, in rare cases, push serotonin too high.

1 of the supplement ingredient on this page reaches Dextromethorphan HBr, Phenylephrine HCl through this category.

Check a real product

Take a Supplement Product? Check the Whole Bottle Against Dextromethorphan HBr, Phenylephrine HCl

Most supplements are combination products — and the interaction may come from an ingredient you didn’t buy it for. Search any product below (or scan its label) and we’ll check every ingredient on it against Dextromethorphan HBr, Phenylephrine HCl.

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Pharmacist Counseling Corner

Dextromethorphan HBr, Phenylephrine HCl & Supplements: Common Questions

What supplements interact with Dextromethorphan HBr, Phenylephrine HCl?
More than you might expect — 197 in total, though they are far from equal: 8 are rated major, 148 moderate, and 41 minor. The ranked list on this page puts the ones that genuinely matter first, and every entry opens a full report on that exact pair. The highest-ranked right now: Grapefruit, Activated Charcoal, Ephedra.
Which Dextromethorphan HBr, Phenylephrine HCl supplement interactions are the most serious?
The 8 major-rated combinations — led by Grapefruit, Activated Charcoal, Ephedra, Lithium and Peyote — deserve real caution: these are the ones generally best avoided, or used only with your prescriber watching. If you take any of them today, don't panic and don't stop anything abruptly — call your pharmacist first. Jump to the ranked list.
Can I take vitamins or supplements while on Dextromethorphan HBr, Phenylephrine HCl?
Usually yes — most people on Dextromethorphan HBr, Phenylephrine HCl can take most supplements. The catch is the exceptions, and they aren't always the exotic ones (St. John's Wort trips up more prescriptions than almost anything sold next to it). Look up each ingredient you actually take in the list above, and treat "no known interaction" as a green-ish light, not a guarantee. Try the label scanner or the interaction checker.
Do brands like Vicks Formula 44D Cough & Head Congestion Relief have the same supplement interactions as Dextromethorphan HBr, Phenylephrine HCl?
Yes — Vicks Formula 44D Cough & Head Congestion Relief all contain Dextromethorphan HBr, Phenylephrine HCl, so everything on this page applies to them equally. Interactions belong to the active drug, never to the brand on the box; the same is true of generics.
Where do these interaction ratings come from?
Every rating comes from the Natural Medicines database — the same evidence-graded reference pharmacists and hospitals use — and each interaction carries three separate grades: severity (how bad it can be), likelihood (how well it's documented in studies and case reports), and an evidence level. Our pharmacists review the content; we never let an AI decide an interaction. See how to read the ratings and our editorial policy.
What about Dextromethorphan HBr, Phenylephrine HCl and my other medications?
This page covers Dextromethorphan HBr, Phenylephrine HCl against supplements and herbal ingredients. Checking Dextromethorphan HBr, Phenylephrine HCl against your other prescription or OTC medications is a different tool — our drug interaction checker covers that side. Head to the drug–drug interaction checker.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Where This Data Comes From — and Why You Can Trust It

🧪 Licensed clinical database

Every interaction verdict on this page comes from Natural Medicines Pro (TRC Healthcare / Therapeutic Research) — the same evidence-graded reference used by pharmacists and hospitals. We license this data directly; we do not scrape it, and no AI invents an interaction.

🧑‍⚕️ Pharmacist review

This page is curated and coded by , Clinical Pharmacist, with additional analysis by the HelloPharmacist Pharmacist Team. Editorial commentary is ours; the licensed interaction records are shown as sourced.

🔄 Kept current

Our interaction database refreshes on a weekly cycle, and this page re-checks the live database every time it’s rebuilt — what you see reflects the database as of September 29, 2026.

🔍 Full transparency

How every dataset on this site is sourced, licensed, and updated is documented publicly: our data sources · editorial policy · how we use AI.

Educational information, not medical advice. An interaction being on file does not mean it will happen to you — and absence of one is not proof of safety. Never start or stop a medication or supplement without talking to your pharmacist or doctor.