Drug & supplement interaction

Mountain Ash + Hydrochlorothiazide, Losartan Potassium

Hydrochlorothiazide, Losartan Potassium brand name: Hyzaar.

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

Mountain Ash has a moderate interaction with Hydrochlorothiazide, Losartan Potassium. Taking large amounts of fresh mountain ash berries may cause kidney damage due to its parasorbic acid constituent.

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

Mountain Ash and Hydrochlorothiazide, Losartan Potassium

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

Moderate

NEPHROTOXIC DRUGS

Why this applies to Hydrochlorothiazide, Losartan Potassium

Hydrochlorothiazide, Losartan Potassium falls under NEPHROTOXIC DRUGS — the group Mountain Ash interacts with.

Taking large amounts of fresh mountain ash berries may cause kidney damage due to its parasorbic acid constituent. Theoretically, taking mountain ash berries with nephrotoxic drugs might increase the risk for kidney damage. Until more is known, advise patients to avoid taking mountain ash berries if they are taking other potentially nephrotoxic drugs.
Some potentially nephrotoxic drugs include cyclosporine (Neoral, Sandimmune); aminoglycosides including amikacin (Amikin), gentamicin (Garamycin, Gentak, others), and tobramycin (Nebcin, others); nonsteroidal anti-inflammatory drugs (NSAIDs) including ibuprofen (Advil, Motrin, Nuprin, others), indomethacin (Indocin), naproxen (Aleve, Anaprox, Naprelan, Naprosyn), piroxicam (Feldene); 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 thing to keep in mind with Hyzaar, which combines hydrochlorothiazide (a water pill) and losartan (a blood pressure medicine). Both of these work directly through your kidneys, and large amounts of fresh mountain ash berries may, at least in theory, stress the kidneys because of a compound called parasorbic acid. Put the two together and the worry is added strain on your kidney function over time.

I want to be honest that this concern is theoretical, based on how the chemistry looks rather than real patient studies. Cooked berries in jam or tea are a different story than concentrated supplement doses. Still, since this medicine already leans on your kidneys (and can affect potassium and hydration), I'd skip strong mountain ash supplements and run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

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

Mountain Ash Also Interacts With Other Medications

Mountain Ash has 354 moderate known drug interactions in our database — the Hydrochlorothiazide, Losartan Potassium one above is one of them. If you take anything else, check it against the full list below.

Moderate 354 No known interaction 2,476 (incl. Hydrochlorothiazide, Losartan Potassium)
Taking anything else?

Check Another of Your Medications Against Mountain Ash

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

Everything else you take

See Every Supplement That Interacts With Hydrochlorothiazide, Losartan Potassium

This page covers Mountain Ash only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydrochlorothiazide, Losartan Potassium page lists 314 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), Asarabacca (major) and Dolomite (major).

By severity: 12 major · 259 moderate · 43 minor.

From our pharmacist’s overview on the Hydrochlorothiazide, Losartan Potassium page

“Grapefruit is the everyday item to know first if you take hydrochlorothiazide with losartan (Hyzaar). It blocks the enzyme that clears losartan, raising drug levels, and it is one of 12 major-rated entries on a list of 314 supplements and herbs, enough serious risk to warrant genuine care.”

Reviewed by 2 · Jul 18, 2026

Open the Hydrochlorothiazide, Losartan Potassium interaction page

One more smart check

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

We hold 1 real supplement products containing Mountain Ash, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Mountain Ash. Your product may carry other ingredients that interact with Hydrochlorothiazide, Losartan Potassium too, on top of Mountain 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 Mountain Ash and Hydrochlorothiazide, Losartan Potassium 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 Mountain Ash
Steady interest

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

29 days ago today
Medication Hydrochlorothiazide, Losartan Potassium
Top 25%

#417 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 Mountain Ash

What is Mountain Ash?

Mountain Ash
  • Sore throat and hoarseness
  • Digestive upset and constipation
  • Cough and chest congestion
  • Mild urinary complaints
  • Source of vitamin C in folk medicine

Mountain ash (rowan) is a northern-hemisphere tree whose bright red berries are traditionally cooked into jams, syrups, and teas. There is very little reliable human research to support any medical use, and raw berries contain compounds that can cause stomach upset, so cooking is important. If you want to try it, talk with your pharmacist or doctor first.

Read the full Mountain Ash monograph & all interactions
Keep checking

Other Drugs & Mountain Ash

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

0Major
354Moderate
0Minor
2,475No known interaction
354 Moderate 2,475 No interaction
Moderate

354 interactions

Showing 60 of 354 moderate interactions — see all 354 on the Mountain Ash page.

No interaction 2,475 drugs checked — show the list

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

Showing the 60 most looked-up of 2,475 medications checked with no known interaction — see the full Mountain Ash list.

See the full Mountain Ash interactions page
See every supplement checked against Hydrochlorothiazide, Losartan Potassium, 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
Mountain Ash monograph › Uses, safety, and every drug interaction in one place Hydrochlorothiazide, Losartan Potassium supplement interactions › Every supplement checked against Hydrochlorothiazide, Losartan Potassium, 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 Mountain Ash and Hydrochlorothiazide, Losartan Potassium Together: Common Questions

Can you take Mountain Ash with Hydrochlorothiazide, Losartan Potassium?
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 Mountain Ash and Hydrochlorothiazide, Losartan Potassium 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 Hydrochlorothiazide, Losartan Potassium and Mountain 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.