Drug & supplement interaction

False Unicorn + 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 False Unicorn can interact with; the most serious is rated moderate. In vitro, false unicorn extract inhibits cytochrome P450 2D6 (CYP2D6) activity.

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

False Unicorn and Dextromethorphan

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

Why Are There 2 Interactions?

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

In vitro, false unicorn extract inhibits cytochrome P450 2D6 (CYP2D6) activity. Theoretically, false unicorn might increase the levels of CYP2D6 substrates. Some of drugs that are CYP2D6 substrates include amitriptyline (Elavil), clozapine (Clozaril), codeine, desipramine (Norpramin), donepezil (Aricept), fentanyl (Duragesic), flecainide (Tambocor), fluoxetine (Prozac), meperidine (Demerol), methadone (Dolophine), metoprolol (Lopressor, Toprol XL), olanzapine (Zyprexa), ondansetron (Zofran), tramadol (Ultram), trazodone (Desyrel), and others.
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 short version: your body relies on a liver enzyme called CYP2D6 to clear dextromethorphan out of your system. In a test-tube study, False Unicorn appeared to slow that enzyme down. If that held true in people, dextromethorphan could hang around longer and build up, which might mean more of its usual effects, things like drowsiness, dizziness, or feeling a bit foggy or unsteady.

I want to keep this in perspective, though. This concern comes only from lab work, not from real patients, so it's mostly theoretical. For a few days of cough relief, it's unlikely to cause big trouble for most folks. Still, since safety data on False Unicorn is thin, it's worth a quick chat with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ho SH, Singh M, Holloway AC, Crankshaw DJ. The effects of commercial preparations of herbal supplements commonly used by women on the biotransformation of fluorogenic substrates by human cytochromes P450. Phytother Res. 2011;25(7):983-9. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

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

In vitro, false unicorn extract inhibits cytochrome P450 3A4 (CYP3A4) activity. Theoretically, false unicorn might increase the levels of CYP3A4 substrates. Drugs that might be affected include some calcium channel blockers (diltiazem, nicardipine, verapamil), chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), glucocorticoids, cisapride (Propulsid), alfentanil (Alfenta), fentanyl (Sublimaze), losartan (Cozaar), fluoxetine (Prozac), midazolam (Versed), omeprazole (Prilosec), ondansetron (Zofran), propranolol (Inderal), fexofenadine (Allegra), and numerous others.
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 your cough medicine. In lab dishes, False Unicorn appears to slow down an enzyme called CYP3A4, which is one of the helpers your liver uses to clear dextromethorphan from your body. If that clearing slows, more of the drug could hang around, which in theory means a bit more of its usual effects like drowsiness, dizziness, or feeling foggy.

The honest part: this is based only on test-tube data, not real people, so it may not matter much in practice. Dextromethorphan is mild and used short-term, but if you're combining it with this herb, it's worth a quick check with your pharmacist or doctor first, especially if you feel unusually sleepy or off.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ho SH, Singh M, Holloway AC, Crankshaw DJ. The effects of commercial preparations of herbal supplements commonly used by women on the biotransformation of fluorogenic substrates by human cytochromes P450. Phytother Res. 2011;25(7):983-9. 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

False Unicorn Also Interacts With Other Medications

False Unicorn has 739 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 739 No known interaction 2,091 (incl. Dextromethorphan)
Taking anything else?

Check Another of Your Medications Against False Unicorn

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

From our Q&A

Questions About False Unicorn 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 False Unicorn 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 False Unicorn 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 False Unicorn as Part of a Dietary Supplement Product? Check It for Interactions

We hold 32 real supplement products containing False Unicorn, each one broken down to its full ingredient list — and combination products often carry several ingredients besides False Unicorn. Your product may carry other ingredients that interact with Dextromethorphan too, on top of False Unicorn — 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 False Unicorn 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 False Unicorn
Top half

#691 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 False Unicorn

What is False Unicorn?

False Unicorn
  • Menstrual cramps
  • Menopausal symptoms
  • Female infertility support
  • Irregular periods
  • Digestive complaints

False Unicorn is a North American plant whose root has long been used in traditional medicine for women's reproductive and menstrual concerns. There is very little reliable human research to show it actually works, and safety has not been well studied, so it should be used with caution and never during pregnancy. Talk to your pharmacist or doctor before trying it.

Read the full False Unicorn 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 & False Unicorn

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

0Major
739Moderate
0Minor
2,090No known interaction
739 Moderate 2,090 No interaction
Moderate

739 interactions

Showing 60 of 739 moderate interactions — see all 739 on the False Unicorn page.

No interaction 2,090 drugs checked — show the list

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

Showing the 60 most looked-up of 2,090 medications checked with no known interaction — see the full False Unicorn list.

See the full False Unicorn 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
False Unicorn 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 False Unicorn and Dextromethorphan Together: Common Questions

Can you take False Unicorn 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 False Unicorn and Dextromethorphan?
Dextromethorphan belongs to more than one drug category, and False Unicorn 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 False Unicorn 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 False Unicorn?

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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.