Drug & supplement interaction

Ash + Macitentan

Macitentan brand name: Opsumit.

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

Ash has a moderate interaction with Macitentan. Theoretically, concomitant use of ash seed with antihypertensive drugs might have additive blood pressure lowering effects.

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

Ash and Macitentan

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Macitentan

Macitentan falls under ANTIHYPERTENSIVE DRUGS — the group Ash interacts with.

Theoretically, concomitant use of ash seed with antihypertensive drugs might have additive blood pressure lowering effects. Animal research shows that ash seed extract can decrease blood pressure. This effect has not been evaluated in humans. Until more is known, use cautiously in patients taking antihypertensive drugs.
Some antihypertensive drugs include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), 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 gist for Opsumit (macitentan). This medicine relaxes blood vessels in your lungs to treat pulmonary arterial hypertension, and it can lower your blood pressure on its own. Ash seed, in animal studies only, also showed a mild blood-pressure-lowering effect. So the worry is that stacking the two could push your pressure down a bit too far.

If that happened, you might feel dizzy, lightheaded, tired, or faint when standing up quickly. I want to be honest though: this hasn't been tested in people, so it's a theoretical concern rather than a proven one. Culinary or tea-sized amounts are unlikely to matter much, but concentrated supplements are a bigger question mark. Please check with your pharmacist or doctor before combining them, and don't change your macitentan.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Montó F, Arce C, Noguera MA, et al. Action of an extract from the seeds of Fraxinus excelsior L. on metabolic disorders in hypertensive and obese animal models. Food Funct. 2014;5(4):786-96. 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

Ash Also Interacts With Other Medications

Ash has 257 moderate known drug interactions in our database — the Macitentan 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. Macitentan)
Taking anything else?

Check Another of Your Medications Against Ash

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

Everything else you take

See Every Supplement That Interacts With Macitentan

This page covers Ash 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

One more smart check

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

We hold 8 real supplement products containing Ash, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ash. Your product may carry other ingredients that interact with Macitentan too, on top of Ash — 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 Ash 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 Ash
Top half

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

29 days ago today
Medication Macitentan
Steady interest

#1,531 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 Ash

What is Ash?

Ash
  • Joint pain and arthritis
  • Fever
  • Constipation
  • Fluid retention (diuretic)
  • Bladder and urinary complaints
  • Weight management and blood sugar

Ash (Fraxinus excelsior and related species) is a tree whose leaves, bark, and seeds have a long history in folk medicine for arthritis, fever, and fluid retention. Solid human evidence is limited for nearly all of these uses, so it should not replace proven treatments. Talk with your pharmacist or doctor before using it, especially if you are pregnant, breastfeeding, or taking other medicines.

Read the full Ash 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.

See full Macitentan drug information
Keep checking

Other Drugs & Ash

Browse every other medication we’ve checked against Ash — 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 Ash page.

No interaction 2,572 drugs checked — show the list

We also checked Ash 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 Ash list.

See the full Ash interactions page
See every supplement checked against Macitentan, 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
Ash monograph › Uses, safety, and every drug interaction in one place Macitentan supplement interactions › Every supplement checked against Macitentan, ranked by severity Macitentan 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 Ash and Macitentan Together: Common Questions

Can you take Ash with Macitentan?
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 Ash and Macitentan 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 Macitentan and Ash?

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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.