Drug & supplement interaction

Onion + Tipiracil Hydrochloride, Trifluridine

Tipiracil Hydrochloride, Trifluridine brand name: Lonsurf.

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 Onion and Tipiracil Hydrochloride, Trifluridine 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 label for Tipiracil Hydrochloride, Trifluridine states a food rule worth keeping to, and 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 Tipiracil Hydrochloride, Trifluridine

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 Tipiracil Hydrochloride, Trifluridine 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 Tipiracil Hydrochloride, Trifluridine and Onion? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Tipiracil Hydrochloride, Trifluridine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Tipiracil Hydrochloride, Trifluridine is filed under a single classification — 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 Tipiracil Hydrochloride, Trifluridine’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 — Tipiracil Hydrochloride, Trifluridine 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. Tipiracil Hydrochloride, Trifluridine)
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 Tipiracil Hydrochloride, Trifluridine May Share a Side Effect

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.

  • 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.

    Tipiracil Hydrochloride, Trifluridine

    Listed in the ADVERSE REACTIONS section of the FDA label for Tipiracil Hydrochloride, Trifluridine. Read the label on DailyMed ›

Reported for Onion but not commonly for Tipiracil Hydrochloride, Trifluridine: a severe allergic reaction, heartburn and migraine.

Effects for Tipiracil Hydrochloride, Trifluridine come from the ADVERSE REACTIONS section of its FDA label; effects for Onion come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

How to take them

Some Tipiracil Hydrochloride, Trifluridine Products Have a Food Rule — Onion Should Not Break It

At least one FDA label for a product containing Tipiracil Hydrochloride, Trifluridine says to take it with food. If you take Onion on an empty stomach out of habit, keep them separate — and take Tipiracil Hydrochloride, Trifluridine with a meal where the label says to.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Tipiracil Hydrochloride, Trifluridine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

2 DOSAGE AND ADMINISTRATION Recommended Dosage : 35 mg/m 2 /dose orally twice daily with food on Days 1 through 5 and Days 8 through 12 of each 28-day cycle.

From the Dosage and Administration section of the FDA label we read for Tipiracil Hydrochloride, Trifluridine — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Everything else you take

See Every Supplement That Interacts With Tipiracil Hydrochloride, Trifluridine

This page covers Onion only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tipiracil Hydrochloride, Trifluridine page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

Open the Tipiracil Hydrochloride, Trifluridine 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 Tipiracil Hydrochloride, Trifluridine, 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 Tipiracil Hydrochloride, Trifluridine 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%

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

29 days ago today
Medication Tipiracil Hydrochloride, Trifluridine
Top 25%

#525 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 13, 2026. The Onion and Tipiracil Hydrochloride, Trifluridine 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 Trifluridine and Tipiracil

What Is Trifluridine and Tipiracil Used For?

Brand name: Lonsurf

Lonsurf (trifluridine and tipiracil) is used to treat adults with metastatic colorectal cancer — either alone or combined with bevacizumab — after prior treatment with several other chemotherapy regimens and targeted therapies.

Lonsurf is also used for adults with metastatic gastric or gastroesophageal junction adenocarcinoma (cancer of the stomach or where the stomach meets the esophagus) who have already received at least two prior chemotherapy regimens.

See full Trifluridine and Tipiracil 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 Tipiracil Hydrochloride, Trifluridine, 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 Tipiracil Hydrochloride, Trifluridine Together: Common Questions

Is it safe to take Onion with Tipiracil Hydrochloride, Trifluridine?
We do not list a known interaction between Onion and Tipiracil Hydrochloride, Trifluridine. 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 Tipiracil Hydrochloride, Trifluridine have any of the same side effects?
Yes — our sources link each of them separately to one 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.
Should I take Onion and Tipiracil Hydrochloride, Trifluridine at the same time of day?
At least one FDA label for a product containing Tipiracil Hydrochloride, Trifluridine says to take it with food. If you take Onion on an empty stomach out of habit, keep them separate and take Tipiracil Hydrochloride, Trifluridine with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Tipiracil Hydrochloride, Trifluridine products can differ — so check the directions on your own box. This is about absorption, not an interaction.
How was the Onion and Tipiracil Hydrochloride, Trifluridine combination checked?
Interactions in our licensed database are recorded against drug classes. Tipiracil Hydrochloride, Trifluridine is filed under 1 classification, and Onion has documented interactions with 5 drug classes — none of Tipiracil Hydrochloride, Trifluridine'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 — Tipiracil Hydrochloride, Trifluridine 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 Tipiracil Hydrochloride, Trifluridine interact with any supplements?
Yes. Tipiracil Hydrochloride, Trifluridine has documented interactions with 17 supplements in our database — Onion is not one of them. The Tipiracil Hydrochloride, Trifluridine 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 Trifluridine and Tipiracil drug information The full plain-English guide to this medication Tipiracil Hydrochloride, Trifluridine supplement interactions Every supplement checked against Tipiracil Hydrochloride, Trifluridine, 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 Tipiracil Hydrochloride, Trifluridine 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.