Drug & supplement interaction

Terminalia + Dextromethorphan

Dextromethorphan brand names: Hold, Benylin Adult, Benylin Pediatric, Theraflu Thin Strips Long Acting Cough, Neo Citran Thin Strips Cough.

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

Dextromethorphan falls into 2 drug categories that Terminalia can interact with; the most serious is rated moderate. Theoretically, use of Terminalia arjuna may increase the levels and clinical effects of CYP2D6 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Terminalia and Dextromethorphan

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Terminalia interacts with whole categories of medication. Dextromethorphan falls into 2 of those categories, so it can interact with Terminalia in 2 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 2

Why this applies to Dextromethorphan

Dextromethorphan falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Terminalia interacts with.

Theoretically, use of Terminalia arjuna may increase the levels and clinical effects of CYP2D6 substrates.
In vitro research shows that Terminalia arjuna extract inhibits CYP2D6 enzymes and reduces CYP2D6 substrate metabolism.
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 for this pairing. Your body relies on an enzyme called CYP2D6 to break down dextromethorphan, the active ingredient in many cough syrups. Lab studies suggest that Terminalia arjuna may slow that enzyme down. If it does, dextromethorphan could clear out more slowly and build up a bit, which might lead to more drowsiness, dizziness, or that lightheaded, foggy feeling some people notice with cough medicine.

I want to be honest about the strength of this, though. It comes only from test-tube research, not from people, so it's mostly theoretical. For occasional cough relief it's probably minor, but if you take Terminalia regularly, run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Varghese A, Savai J, Pandita N, Gaud RS. In vitro modulatory effects of Terminalia arjuna, arjunic acid, arjunetin, and arjungenin on CYP3A4, CYP2D6, and CYP2C9 enzyme activity in human liver microsomes. Toxicology Reports. 2015(2):806-16. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

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

Theoretically, use of Terminalia arjuna may increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that Terminalia arjuna extract inhibits CYP3A4 enzymes and reduces CYP3A4 substrate metabolism.
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 of it: lab studies suggest Terminalia arjuna may slow down the CYP3A4 enzyme, one of the pathways your body uses to clear dextromethorphan. If that pathway is slowed, more of the cough medicine could linger in your system. In practice that might mean a bit more drowsiness, dizziness, or feeling foggy than usual.

I want to be honest about the evidence here, though. This interaction comes only from test-tube research, not from people, so it's theoretical and may not show up in real life at all. Dextromethorphan is also a short-term, as-needed cough remedy, which limits the risk. Still, if you're combining the two, a quick chat with your pharmacist or doctor is the safe move.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Varghese A, Savai J, Pandita N, Gaud RS. In vitro modulatory effects of Terminalia arjuna, arjunic acid, arjunetin, and arjungenin on CYP3A4, CYP2D6, and CYP2C9 enzyme activity in human liver microsomes. Toxicology Reports. 2015(2):806-16. 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

Terminalia Also Interacts With Other Medications

Terminalia has 932 moderate known drug interactions in our database — the Dextromethorphan one above is among them. If you take anything else, check it against the full list below.

Moderate 932 No known interaction 1,898 (incl. Dextromethorphan)
Taking anything else?

Check Another of Your Medications Against Terminalia

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

From our Q&A

Questions About Terminalia or Dextromethorphan

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

This page covers Terminalia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dextromethorphan 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 page

“A glass of grapefruit juice can push dextromethorphan (Benylin, Hold, and other cough medicines) to higher levels than intended, one of four major-rated entries among the 171 supplements and herbs on file, and the list as a whole warrants real care. Most interactions trace back to the liver enzymes (CYP3A4 and CYP2D6) that clear dextro…”

Reviewed by 2 · Jul 18, 2026

Open the Dextromethorphan interaction page

One more smart check

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

We hold 306 real supplement products containing Terminalia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Terminalia. Your product may carry other ingredients that interact with Dextromethorphan too, on top of Terminalia — 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 Terminalia and Dextromethorphan 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 Terminalia
Top 25%

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

29 days ago today
Medication Dextromethorphan
Top 5%

#80 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 Terminalia

What is Terminalia?

Terminalia
  • Heart health and circulation
  • Digestive problems (constipation, diarrhea)
  • Cholesterol support
  • Antioxidant and anti-inflammatory support
  • Immune support

Terminalia is a group of traditional Ayurvedic tree species (most notably Terminalia arjuna) used for heart, digestive, and general wellness purposes. Some small studies suggest possible benefits for heart and cholesterol health, but the evidence is limited and not strong enough to recommend it as a treatment. Talk to your pharmacist or doctor before using it, especially if you have a heart condition.

Read the full Terminalia monograph & all interactions
Medication

About Dextromethorphan

What Is Dextromethorphan Used For?

Brand names: Hold, Benylin Adult, Benylin Pediatric, Theraflu Thin Strips Long Acting Cough, Neo Citran Thin Strips Cough

Dextromethorphan temporarily relieves cough due to minor throat and bronchial irritation, such as the kind that comes with the common cold or breathing in irritants. It also helps reduce the urge to cough so you — or your child — can get to sleep.

Some products, including CVS Long Acting Cough and Premier Value Tussin Cough oral liquids, are also indicated to help loosen phlegm (mucus) and thin bronchial secretions to help drain the airways.

See full Dextromethorphan drug information
Keep checking

Other Drugs & Terminalia

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

0Major
932Moderate
0Minor
1,897No known interaction
932 Moderate 1,897 No interaction
Moderate

932 interactions

Showing 60 of 932 moderate interactions — see all 932 on the Terminalia page.

No interaction 1,897 drugs checked — show the list

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

Showing the 60 most looked-up of 1,897 medications checked with no known interaction — see the full Terminalia list.

See the full Terminalia interactions page
See every supplement checked against Dextromethorphan, 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
Terminalia monograph › Uses, safety, and every drug interaction in one place Dextromethorphan supplement interactions › Every supplement checked against Dextromethorphan, ranked by severity Dextromethorphan drug information › The full plain-English guide to this medication 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 Terminalia and Dextromethorphan Together: Common Questions

Can you take Terminalia with Dextromethorphan?
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 2 interactions listed for Terminalia and Dextromethorphan?
Dextromethorphan belongs to more than one drug category, and Terminalia 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 Terminalia and Dextromethorphan 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 and Terminalia?

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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.