Drug & supplement interaction

Marsh Labrador Tea + Macitentan

Macitentan brand name: Opsumit.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between Marsh Labrador Tea and Macitentan in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Marsh Labrador Tea and Macitentan

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Macitentan and Marsh Labrador Tea in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Marsh Labrador Tea safety at a glance

Marsh Labrador Tea overall Use caution The plant contains toxic grayanotoxins, so any internal use carries a risk of poisoning.
Pregnancy Likely Unsafe When used orally; avoid using. Marsh Labrador tea is considered to be a potential uterine stimulant and abortifacient. Read the full pregnancy detail
Breastfeeding Avoid Not enough safety data and it contains potentially toxic substances, so avoid use.

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Macitentan and Marsh Labrador Tea? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Macitentan

Interactions in our licensed database are recorded against drug classes, not just single drug names. Macitentan is filed under 4 classifications — including antihypertensive drugs, hepatotoxic drugs, cytochrome p450 3a4 (cyp3a4) substrates. Marsh Labrador Tea has documented interactions with 1 drug class — the most serious being cns depressants (moderate) — and none of Macitentan’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Marsh Labrador Tea Does Interact With Other Medications

Marsh Labrador Tea has 248 moderate known drug interactions in our database — Macitentan isn’t one of them. If you take anything else, check it against the full list below.

Moderate 248 No known interaction 2,582 (incl. Macitentan)
Taking anything else?

Check Another of Your Medications Against Marsh Labrador Tea

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

What to actually watch for

What Marsh Labrador Tea Itself Has Been Linked To

This is not an interaction — nothing below involves Macitentan. It is the side-effect record for Marsh Labrador Tea on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Marsh Labrador Tea, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • Seizures Worth acting on Additional detail

    “Orally, large amounts of marsh Labrador tea can cause poisoning due to its ledol constituent (2). The essential oil of marsh Labrador tea can cause severe irritation of the gastrointestinal tract, vomiting, diarrhea, irritation and damage to the kidneys and urinary tract, heavy perspiration, myalgias, and arthralgias.”

    Marsh Labrador Tea · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 2. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
    2. 97164. Dampc A, Luczkiewicz M. Bog Labrador tea--the aromatic beverage and spice: a review of origin, processing and safety. J Sci Food Agric. 2015;95(8):1577-83. PubMed

    “Orally, ledol, a constituent of marsh Labrador tea essential oil, can cause central nervous system excitation in a dose-dependent manner. Small amounts of ledol can lead to mild stimulating effects similar to caffeine, while larger doses can lead to spasms, seizures, paralysis, and even death.”

    Marsh Labrador Tea · Natural Medicines adverse-effect record, reported in epilepsy.

    1 source cited
    1. 97164. Dampc A, Luczkiewicz M. Bog Labrador tea--the aromatic beverage and spice: a review of origin, processing and safety. J Sci Food Agric. 2015;95(8):1577-83. PubMed
  • Sweating Additional detail

    Recorded for Marsh Labrador Tea in the same Natural Medicines adverse-effect record shown under Seizures above.

  • Diarrhea / Vomiting Additional detail

    “Orally, ledol, a constituent of the essential oil of marsh Labrador tea, can cause gastrointestinal irritation resulting in vomiting, gastroenteritis, and diarrhea.”

    Marsh Labrador Tea · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 97164. Dampc A, Luczkiewicz M. Bog Labrador tea--the aromatic beverage and spice: a review of origin, processing and safety. J Sci Food Agric. 2015;95(8):1577-83. PubMed

Everything above comes from the Natural Medicines adverse-effect record for Marsh Labrador Tea — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Macitentan’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Macitentan column appears here.

Special populations

Marsh Labrador Tea in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally; avoid using. Marsh Labrador tea is considered to be a potential uterine stimulant and abortifacient.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Everything else you take

See Every Supplement That Interacts With Macitentan

This page covers Marsh Labrador Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Macitentan page lists 253 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), Beer (major) and Grapefruit (major).

By severity: 9 major · 205 moderate · 39 minor.

From our pharmacist’s overview on the Macitentan page

“If you take macitentan (Opsumit) for pulmonary arterial hypertension, study this page rather than skim it. It lists 253 supplement and herbal ingredients, nine rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Macitentan interaction page

How much people look this up

Where Marsh Labrador Tea and Macitentan 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 Marsh Labrador Tea
Steady interest

#1,016 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Macitentan
Top half

#974 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Marsh Labrador Tea reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The Marsh Labrador Tea and Macitentan records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Marsh Labrador Tea

What is Marsh Labrador Tea?

Marsh Labrador Tea
  • Colds and respiratory complaints
  • Cough and congestion
  • Mild aches and joint discomfort
  • Topical relief of skin irritation, swelling, and insect bites
  • Traditional use as a diuretic

Marsh Labrador tea is a bog-growing shrub used in folk medicine for coughs, colds, and skin problems, but high-quality human evidence for any use is lacking. Because it contains grayanotoxins (andromedotoxin) that can be poisonous, it is not considered safe for routine use, and pregnant or breastfeeding people should avoid it.

Rhododendron tomentosum · Ericaceae · Leaves and flowering twigs (and an essential oil distilled from them) · Tea (infusion), essential oil, topical preparations

An interaction check asks whether these two react with each other — it does not ask whether Marsh Labrador Tea is a good idea for someone in your situation. Here is what our Marsh Labrador Tea record says about it on its own.

Marsh Labrador Tea: dosing

There is no established safe or standardized dose for Marsh Labrador tea. Because the plant naturally contains toxic grayanotoxins, even traditional preparations carry risk, and stronger or longer brews increase that risk.If you choose to use a commercial product, follow the directions on the label exactly and do not exceed them. Never assume that "natural" means harmless.

From our Marsh Labrador Tea monograph — the full record covers uses, side effects and every documented interaction.

Read the full Marsh Labrador Tea monograph & all interactions
Medication

About Macitentan

What Is Macitentan Used For?

Brand name: Opsumit

Macitentan tablets — sold under the brand name Opsumit — are used to treat pulmonary arterial hypertension (PAH, WHO Group I), a type of high blood pressure in the arteries of the lungs. The goal is to slow the disease from getting worse and to lower the chance of being hospitalized because of PAH.

In the key clinical study, macitentan was used in adults with mainly moderate-to-severe PAH symptoms. Patients had PAH caused by unknown or inherited causes, connective tissue disorders, or congenital heart disease with repaired shunts.

Most-Reported Side Effects for Macitentan

From FAERS, the FDA’s public side-effect reporting system (68,860 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 11,958 reports
Headache 8,323 reports
Diarrhea 6,584 reports
Nausea 5,972 reports
Fatigue 5,041 reports
See full Macitentan drug information
Keep checking

Other Drugs & Marsh Labrador Tea

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

0Major
248Moderate
0Minor
2,581No known interaction
248 Moderate 2,581 No interaction
Moderate

248 interactions

Showing 60 of 248 moderate interactions — see all 248 on the Marsh Labrador Tea page.

No interaction 2,581 drugs checked — show the list

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

Showing the 60 most looked-up of 2,581 medications checked with no known interaction — see the full Marsh Labrador Tea list.

See the full Marsh Labrador Tea interactions page
See every supplement checked against Macitentan, ranked by severity
Evidence & sources

Marsh Labrador Tea References

The 3 references that drive our Marsh Labrador Tea monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Dampc A, Luczkiewicz M. Bog Labrador tea--the aromatic beverage and spice: a review of origin, processing and safety. J Sci Food Agric. 2015;95(8):1577-83. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Marsh Labrador Tea and Macitentan Together: Common Questions

Is it safe to take Marsh Labrador Tea with Macitentan?
We do not list a known interaction between Marsh Labrador Tea and Macitentan. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Marsh Labrador Tea and Macitentan combination checked?
Interactions in our licensed database are recorded against drug classes. Macitentan is filed under 4 classifications, and Marsh Labrador Tea has documented interactions with 1 drug class — none of Macitentan's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Marsh Labrador Tea interact with any other medications?
Yes. Marsh Labrador Tea has 248 documented drug interactions in our database — Macitentan is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Macitentan interact with any supplements?
Yes. Macitentan has documented interactions with 253 supplements in our database — Marsh Labrador Tea is not one of them. The Macitentan interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Marsh Labrador Tea monograph Uses, safety profile, and every drug interaction in one place Macitentan drug information The full plain-English guide to this medication Macitentan supplement interactions Every supplement checked against Macitentan, 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 References The 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Macitentan and Marsh Labrador Tea?

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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.