Drug & supplement interaction

Onion + Isosorbide Mononitrate

Isosorbide Mononitrate brand names: Imdur, Angeze, Dynamin, Elantan, Ismo, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Onion and Isosorbide Mononitrate 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

Onion and Isosorbide Mononitrate

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 Isosorbide Mononitrate and Onion 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.

Onion safety at a glance

Onion overall Generally safe Onion as a food is generally safe for most people; concentrated supplements are less studied.
Pregnancy Use caution Food amounts are considered fine, but concentrated supplement doses are not well studied and should be avoided.
Breastfeeding Use caution Food amounts are likely fine, but there is not enough evidence on medicinal supplement doses.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Isosorbide Mononitrate and Onion? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Isosorbide Mononitrate

Interactions in our licensed database are recorded against drug classes, not just single drug names. Isosorbide Mononitrate is filed under 3 classifications — nitrates, vasodilators, oral drugs. Onion has documented interactions with 5 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate), antidiabetes drugs (moderate) and aspirin (moderate) — and none of Isosorbide Mononitrate’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

Onion Does Interact With Other Medications

Onion has 275 moderate known drug interactions in our database — Isosorbide Mononitrate isn’t one of them. If you take anything else, check it against the full list below.

Moderate 275 No known interaction 2,555 (incl. Isosorbide Mononitrate)
Taking anything else?

Check Another of Your Medications Against Onion

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

What to actually watch for

No Interaction Found — But Data Suggests Onion and Isosorbide Mononitrate 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.

  • Migraine Additional detail

    Onion

    “Allergy to onion is rare, although there are reports of symptoms to both oral and topical exposure. In one case, oral exposure or the aroma of onions caused the sensation of throat closing in an allergic woman. In a 35-year-old man, cooked onion ingestion triggered anaphylaxis. In another case, the smell of onion was identified as a trigger for migraines in a 32-year-old female.”

    Onion · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    4 sources cited
    1. 41752. Moneret-Vautrin, D. A., Morisset, M., Lemerdy, P., Croizier, A., and Kanny, G. Food allergy and IgE sensitization caused by spices: CICBAA data (based on 589 cases of food allergy). Allerg.Immunol.(Paris) 2002;34(4):135-140.
    2. 101743. Armentia A, Martín-Armentia S, Pineda F, et al. Allergic hypersensitivity to garlic and onion in children and adults. Allergol Immunopathol (Madr). 2019. pii: S0301-0546(19)30091-6. PubMed
    3. 88404. Roussos AP, Hirsch AR. Alliaceous migraines. Headache 2014;54(2):378-82. PubMed
    4. 101742. Albanesi M, Pasculli C, Giliberti L, et al. Immunological characterization of onion (Allium cepa) allergy. Postepy Dermatol Alergol. 2019;36(1):98-103. PubMed

    Isosorbide Mononitrate

    Listed in the ADVERSE REACTIONS section of the FDA label for Isosorbide Mononitrate. Read the label on DailyMed ›

  • Stomach pain Additional detail

    Onion

    “Orally, onion is well tolerated. Topically, onion is generally well tolerated.

    Most Common Adverse Effects:

    Orally: Abdominal pain, heartburn.

    Topically: Eczema, irritation.

    Serious Adverse Effects (Rare):

    All ROAs: Anaphylaxis in sensitive individuals.”

    Onion · Natural Medicines adverse-effect record, reported in dyspepsia.

    Isosorbide Mononitrate

    Listed in the ADVERSE REACTIONS section of the FDA label for Isosorbide Mononitrate. Read the label on DailyMed ›

Reported for Onion but not commonly for Isosorbide Mononitrate: a severe allergic reaction and heartburn.

Effects for Isosorbide Mononitrate come from the ADVERSE REACTIONS section of its FDA label; effects for Onion come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 20,621 voluntary FDA FAERS reports for Isosorbide Mononitrate 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.

Overlapping uses

What Isosorbide Mononitrate Is Prescribed For, and What Onion Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Isosorbide Mononitrate is a prescription medicine with approved uses on its FDA label. Onion is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Isosorbide Mononitrate is prescribed for: Isosorbide is used to prevent angina pectoris — chest pain or tightness caused by coronary artery disease. Both isosorbide dinitrate tablets and isosorbide mononitrate tablets (including Monoket and Isordil) are used for this purpose. Important: none of these oral formulations work fast enough to stop a chest pain episode that has already started. They are taken on a schedule to prevent angina, not to treat it in the moment.

Onion has been studied for:

  • Angina studied, not established Onion has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Onion for angina

    Although there has been interest in using oral onion for angina, there is insufficient reliable information about the clinical effects of onion for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Isosorbide Mononitrate on your own; if you are taking Onion for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Onion or Isosorbide Mononitrate

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

This page covers Onion only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Isosorbide Mononitrate page lists 22 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Coleus (major), Hawthorn (major) and Beer (moderate).

By severity: 4 major · 9 moderate · 9 minor.

From our pharmacist’s overview on the Isosorbide Mononitrate page

“Isosorbide mononitrate (Imdur) is taken daily to prevent angina by keeping blood vessels relaxed, and the 22 supplements and herbs on this page deserve careful reading, not a shrug. Four carry major ratings, and they pull in different directions.”

Reviewed by 2 · Jul 18, 2026

Open the Isosorbide Mononitrate interaction page

One more smart check

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

We hold 1,061 real supplement products containing Onion, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Onion. Even though Onion itself has no known interaction with Isosorbide Mononitrate, 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 Onion and Isosorbide Mononitrate 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 Onion
Top 25%

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

29 days ago today
Medication Isosorbide Mononitrate
Steady interest

#2,537 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 Onion reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Onion and Isosorbide Mononitrate 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 Onion

What is Onion?

Onion
  • Colds and respiratory symptoms
  • Heart and cholesterol health
  • Blood sugar support
  • Antimicrobial and wound care
  • Scar appearance (topical gels)

Onion is a common food with a long history in traditional medicine, and it contains antioxidants like quercetin and sulfur compounds. Eating onion as part of a balanced diet is safe for most people, but high-dose supplements have only limited human evidence for any specific health condition. Talk with your pharmacist or doctor before using concentrated onion products for a medical reason.

Allium cepa · Amaryllidaceae · Bulb (and sometimes the green leaves and extracted juice) · Fresh bulb, juice, dried powder, capsules, extracts, and topical gels

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

Onion: dosing

There is no official standardized dose of onion for any health condition. As a food, onion is simply eaten in normal cooking amounts. For supplements, gels, and extracts, the right amount depends on the specific product and how concentrated it is.If you choose to use an onion supplement, follow the directions on the product label and do not exceed the recommended amount.

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

Read the full Onion monograph & all interactions
Medication

About Isosorbide

What Is Isosorbide Used For?

Brand names: Imdur, Angeze, Dynamin, Elantan, Ismo, Chemydur 60XL, Elantan LA, Isib 60XL, Ismo Retard, Isodur, Isotard, Modisal LA, Modisal XL, Monomax SR, Monomax XL, Angeze SR, Monomil XL, Monosorb XL, Zemon

Isosorbide is used to prevent angina pectoris — chest pain or tightness caused by coronary artery disease. Both isosorbide dinitrate tablets and isosorbide mononitrate tablets (including Monoket and Isordil) are used for this purpose.

Important: none of these oral formulations work fast enough to stop a chest pain episode that has already started. They are taken on a schedule to prevent angina, not to treat it in the moment.

Most-Reported Side Effects for Isosorbide Mononitrate

From FAERS, the FDA’s public side-effect reporting system (20,621 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 1,568 reports
Dizziness 1,464 reports
Fatigue 1,314 reports
Diarrhea 1,311 reports
Nausea 1,284 reports
See full Isosorbide drug information
Keep checking

Other Drugs & Onion

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

0Major
275Moderate
0Minor
2,554No known interaction
275 Moderate 2,554 No interaction
Moderate

275 interactions

Showing 60 of 275 moderate interactions — see all 275 on the Onion page.

No interaction 2,554 drugs checked — show the list

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

Showing the 60 most looked-up of 2,554 medications checked with no known interaction — see the full Onion list.

See the full Onion interactions page
See every supplement checked against Isosorbide Mononitrate, ranked by severity
Evidence & sources

Onion References

The 26 references that drive our Onion 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. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Bruynzeel DP. Bulb dermatitis. Dermatological problems in the flower bulb industries. Contact Dermatitis 1997;37:70-7.
  4. Eberhard P, Gall HM, Muller I, Moller R. Dramatic augmentation of a food allergy by acetylsalicylic acid. J Allergy Clin Immunol 2000;105:844 PubMed
  5. Teyssier, C., Amiot, M. J., Mondy, N., Auger, J., Kahane, R., and Siess, M. H. Effect of onion consumption by rats on hepatic drug-metabolizing enzymes. Food Chem.Toxicol. 2001;39(10):981-987. PubMed
  6. Moneret-Vautrin, D. A., Morisset, M., Lemerdy, P., Croizier, A., and Kanny, G. Food allergy and IgE sensitization caused by spices: CICBAA data (based on 589 cases of food allergy). Allerg.Immunol.(Paris) 2002;34(4):135-140.
  7. van Ketel, W. G. and de Haan, P. Occupational eczema from garlic and onion. Contact Dermatitis 1978;4(1):53-54. PubMed
  8. Mathew, P. T. and Augusti, K. T. Hypoglycaemic effects of onion, Allium cepa Linn. on diabetes mellitus - a preliminary report. Indian J.Physiol Pharmacol. 1975;19(4):213-217.
  9. Campos, K. E., Diniz, Y. S., Cataneo, A. C., Faine, L. A., Alves, M. J., and Novelli, E. L. Hypoglycaemic and antioxidant effects of onion, Allium cepa: dietary onion addition, antioxidant activity and hypoglycaemic effects on diabetic rats. Int J Food S
  10. Bajaj, J. S., Shaker, R., and Hogan, W. J. Esophageal veggie spasms: a food-specific cause of chest distress. Am.J Gastroenterol. 2004;99(7):1396-1398. PubMed
  11. El Demerdash, F. M., Yousef, M. I., and El Naga, N. I. Biochemical study on the hypoglycemic effects of onion and garlic in alloxan-induced diabetic rats. Food Chem.Toxicol. 2005;43(1):57-63. PubMed
  12. Hubbard, G. P., Wolffram, S., de Vos, R., Bovy, A., Gibbins, J. M., and Lovegrove, J. A. Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pil
  13. Kook, S., Kim, G. H., and Choi, K. The antidiabetic effect of onion and garlic in experimental diabetic rats: meta-analysis. J Med Food 2009;12(3):552-560. PubMed
  14. Sharma, K. K., Gupta, R. K., Gupta, S., and Samuel, K. C. Antihyperglycemic effect of onion: effect on fasting blood sugar and induced hyperglycemia in man. Indian J.Med.Res. 1977;65(3):422-429.
  15. Jain, R. C., Vyas, C. R., and Mahatma, O. P. Letter: Hypoglycaemic action of onion and garlic. Lancet 12-29-1973;2(7844):1491.

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 Onion and Isosorbide Mononitrate Together: Common Questions

Is it safe to take Onion with Isosorbide Mononitrate?
We do not list a known interaction between Onion and Isosorbide Mononitrate. 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 Onion and Isosorbide Mononitrate have any of the same side effects?
Yes — our sources link each of them separately to 2 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.
Are Onion and Isosorbide Mononitrate used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Onion in each. That is a conversation for your prescriber, especially if Isosorbide Mononitrate is being adjusted to a target.
How was the Onion and Isosorbide Mononitrate combination checked?
Interactions in our licensed database are recorded against drug classes. Isosorbide Mononitrate is filed under 3 classifications, and Onion has documented interactions with 5 drug classes — none of Isosorbide Mononitrate'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 Onion interact with any other medications?
Yes. Onion has 275 documented drug interactions in our database — Isosorbide Mononitrate 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 Isosorbide Mononitrate interact with any supplements?
Yes. Isosorbide Mononitrate has documented interactions with 22 supplements in our database — Onion is not one of them. The Isosorbide Mononitrate 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

Onion monograph Uses, safety profile, and every drug interaction in one place Isosorbide drug information The full plain-English guide to this medication Isosorbide Mononitrate supplement interactions Every supplement checked against Isosorbide Mononitrate, 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 26 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Isosorbide Mononitrate and Onion?

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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.