Drug & supplement interaction

White Horehound + Mecamylamine

Mecamylamine brand name: Inversine.

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

White Horehound has a moderate interaction with Mecamylamine. Evidence from animal research suggests that taking white horehound extract lowers blood pressure.

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

White Horehound and Mecamylamine

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Mecamylamine

Mecamylamine falls under ANTIHYPERTENSIVE DRUGS — the group White Horehound interacts with.

Evidence from animal research suggests that taking white horehound extract lowers blood pressure. Theoretically, taking white horehound with antihypertensive drugs might enhance therapeutic effects and increase the risk of hypotension. Some antihypertensive drugs include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many 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

Mecamylamine is a fairly old and potent blood pressure medicine that works by blocking nerve signals (it's a ganglionic blocker). It already has a strong tendency to drop your blood pressure, especially when you stand up. The concern here is simple: some animal studies suggest white horehound may lower blood pressure too. Stacking the two could, in theory, push your pressure down farther than intended.

If that happens, you might feel dizzy, lightheaded, weak, or even faint when you stand up quickly. Keep in mind this is a theoretical caution based on lab and animal data, not proven in people, and a lozenge-sized flavoring amount is unlikely to matter much. Still, given how powerful mecamylamine is, please check with your pharmacist or doctor before using horehound supplements.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. El Bardai, S., Lyoussi, B., Wibo, M., and Morel, N. Pharmacological evidence of hypotensive activity of Marrubium vulgare and Foeniculum vulgare in spontaneously hypertensive rat. Clin Exp Hypertens. 2001;23(4):329-343.
  2. El Bardai, S., Lyoussi, B., Wibo, M., and Morel, N. Comparative study of the antihypertensive activity of Marrubium vulgare and of the dihydropyridine calcium antagonist amlodipine in spontaneously hypertensive rat. Clin Exp Hypertens. 2004;26(6):465-474 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

White Horehound Also Interacts With Other Medications

White Horehound has 257 moderate known drug interactions in our database — the Mecamylamine one above is one of them. If you take anything else, check it against the full list below.

Moderate 257 No known interaction 2,573 (incl. Mecamylamine)
Taking anything else?

Check Another of Your Medications Against White Horehound

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

Everything else you take

See Every Supplement That Interacts With Mecamylamine

This page covers White Horehound only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mecamylamine page lists 136 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Tyramine (major) and Adrafinil (moderate).

By severity: 4 major · 111 moderate · 21 minor.

From our pharmacist’s overview on the Mecamylamine page

“Mecamylamine (Inversine) is a potent blood pressure medicine, and its interaction list warrants real vigilance, since 119 of the 136 ingredients on file affect blood pressure themselves. Most add to the drug's effect and can drop pressure too far, fish oil among them, while a few push the other way.”

Reviewed by 2 · Jul 18, 2026

Open the Mecamylamine interaction page

How much people look this up

Where White Horehound and Mecamylamine 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 White Horehound
Steady interest

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

29 days ago today
Medication Mecamylamine
Steady interest

#2,487 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 White Horehound

What is White Horehound?

White Horehound
  • Cough and chest congestion
  • Sore throat
  • Bronchitis
  • Digestive upset and poor appetite
  • Bloating and gas

White horehound is a traditional bitter herb used mainly for coughs, sore throats, and mild digestive complaints, and it is a common flavoring in old-fashioned cough drops. Solid human evidence supporting these uses is limited, so view it as a folk remedy rather than a proven treatment. Talk to your pharmacist or doctor before using it, and avoid it during pregnancy.

Read the full White Horehound monograph & all interactions
Keep checking

Other Drugs & White Horehound

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

0Major
257Moderate
0Minor
2,572No known interaction
257 Moderate 2,572 No interaction
Moderate

257 interactions

Showing 60 of 257 moderate interactions — see all 257 on the White Horehound page.

No interaction 2,572 drugs checked — show the list

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

Showing the 60 most looked-up of 2,572 medications checked with no known interaction — see the full White Horehound list.

See the full White Horehound interactions page
See every supplement checked against Mecamylamine, 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
White Horehound monograph › Uses, safety, and every drug interaction in one place Mecamylamine supplement interactions › Every supplement checked against Mecamylamine, 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 White Horehound and Mecamylamine Together: Common Questions

Can you take White Horehound with Mecamylamine?
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 White Horehound and Mecamylamine 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 Mecamylamine and White Horehound?

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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.