Drug & supplement interaction

Holly + Losartan Potassium

Losartan Potassium brand name: Cozaar.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Holly and Losartan Potassium 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Holly and Losartan Potassium

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 Losartan Potassium and Holly 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.

Worth understanding: our licensed dataset holds no drug-interaction record for Holly at all — not against Losartan Potassium, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

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.

Holly safety at a glance

Holly overall Use caution The berries are toxic if eaten, and there is little safety data on leaf preparations.
Pregnancy Unsafe When berries are ingested. There is insufficient reliable information available about the safety of holly leaves; avoid using. Read the full pregnancy detail
Breastfeeding Unsafe When berries are ingested. There is insufficient reliable information available about the safety of holly leaves; avoid using. Read the full breastfeeding detail

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 Losartan Potassium and Holly? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Holly and Losartan Potassium May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Diarrhea / Nausea / Vomiting reported in 5.9% of FDA reports for Losartan Potassium Additional detail

    Holly

    “Orally, ingestion of holly leaf can cause GI irritation, diarrhea, nausea, and vomiting (6,18). Holly leaf spines may tear or puncture skin or mucous membranes (6). Ingestion of as few as 2 holly berries can cause vomiting and diarrhea in small children (6). Ingestion of more than 5 holly berries can cause nausea, vomiting, and diarrhea (6,18). Ingestion of 20-30 holly berries can cause death (18).”

    Holly · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
    2. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    “Orally, ingestion of holly leaf can cause GI irritation, diarrhea, nausea, and vomiting (6,18). Holly leaf spines may tear or puncture skin or mucous membranes (6). Ingestion of as few as 2 holly berries can cause vomiting and diarrhea in small children (6). Ingestion of more than 5 holly berries can cause nausea, vomiting, and diarrhea (6,18).”

    Holly · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
    2. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Losartan Potassium

    Listed in the ADVERSE REACTIONS section of the FDA label for Losartan Potassium, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Effects for Losartan Potassium come from the ADVERSE REACTIONS section of its FDA label; effects for Holly come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 89,498 voluntary FDA FAERS reports for Losartan Potassium that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Holly in Pregnancy & Breastfeeding

Pregnancy And Lactation Unsafe

When berries are ingested. There is insufficient reliable information available about the safety of holly leaves; avoid using.

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

From our Q&A

Questions About Holly or Losartan Potassium

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Holly or Losartan Potassium, 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 Losartan Potassium

This page covers Holly only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Losartan Potassium 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), Grapefruit (major) and St. John's Wort (major).

By severity: 6 major · 205 moderate · 42 minor.

From our pharmacist’s overview on the Losartan Potassium page

“Losartan potassium (Cozaar) treats high blood pressure, and this is a list to respect, because six of its 253 supplement interactions carry a major rating. Most entries do one of two things.”

Reviewed by 2 · Jul 18, 2026

Open the Losartan Potassium interaction page

One more smart check

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

We hold 11 real supplement products containing Holly, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Holly. Even though Holly itself has no known interaction with Losartan Potassium, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Holly and 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 Holly
Steady interest

#1,324 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Losartan Potassium
Top 10

#6 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 Holly reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Holly and Losartan Potassium records this page draws on were last updated July 10, 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 Holly

What is Holly?

  • Fever
  • Cough and chest congestion
  • Joint pain (traditional use)
  • Digestive complaints
  • Mild diuretic

Holly (Ilex aquifolium) is a common ornamental shrub whose bright red berries are poisonous and should never be eaten. There is very little reliable human evidence supporting any health benefit of holly leaves, and because of safety concerns it is generally best avoided as a supplement unless guided by a knowledgeable healthcare professional.

Ilex aquifolium · Aquifoliaceae · Leaves and berries (and bark in some traditions) · Dried leaf tea, tinctures, and homeopathic preparations; berries are not used as a supplement

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

Holly: dosing

There is no established or standardized dose for holly, because it has not been properly studied as a medicine. We cannot provide a safe recommended amount.If you choose to use a commercial holly product despite the limited evidence, follow the directions on the label exactly and never exceed them.

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

Read the full Holly monograph & all interactions
Medication

About Losartan

What Is Losartan Used For?

Brand name: Cozaar

Losartan tablets — available as branded Cozaar and several generic products — are used to treat high blood pressure (hypertension) in adults and children 6 years and older. Lowering blood pressure reduces the risk of strokes and heart attacks. Losartan tablets are also used to reduce the risk of stroke in people with high blood pressure who also have left ventricular hypertrophy (an enlarged left side of the heart). Note: evidence suggests this stroke-risk benefit may not apply to Black patients.

Losartan tablets are additionally approved to protect the kidneys in people with type 2 diabetes, high blood pressure, and signs of kidney damage (diabetic nephropathy). Arbli, the oral suspension form, shares these same approved uses.

Most-Reported Side Effects for Losartan Potassium

From FAERS, the FDA’s public side-effect reporting system (89,498 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 6,464 reports
Nausea 5,301 reports
Diarrhea 5,184 reports
Dyspnea 4,689 reports
Dizziness 4,429 reports
See full Losartan drug information
Keep checking

Other Drugs & Holly

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Holly list.

See the full Holly interactions page
See every supplement checked against Losartan Potassium, ranked by severity
Evidence & sources

Holly References

The 2 references that drive our Holly 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

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 Holly and Losartan Potassium Together: Common Questions

Is it safe to take Holly with Losartan Potassium?
We do not list a known interaction between Holly and Losartan Potassium. 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.
Do Holly and Losartan Potassium have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Does Losartan Potassium interact with any supplements?
Yes. Losartan Potassium has documented interactions with 253 supplements in our database — Holly is not one of them. The Losartan Potassium 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

Holly monograph Uses, safety profile, and every drug interaction in one place Losartan drug information The full plain-English guide to this medication Losartan Potassium supplement interactions Every supplement checked against 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 References The 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Losartan Potassium and Holly?

Our pharmacists answer your medication & supplement questions — free.

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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.