Drug & supplement interaction

Tomato + Metformin

Metformin brand names: Glucophage, Metformin.

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 Tomato and Metformin 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

Tomato and Metformin

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 Metformin and Tomato 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 Tomato at all — not against Metformin, 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.

Tomato safety at a glance

Tomato overall Generally safe Tomato as a food is safe for most people; concentrated supplements are less studied.
Pregnancy Likely Safe When the tomato fruit or its products are consumed in typical food amounts. There is insufficient reliable information available about the safety of tomato extr... Read the full pregnancy detail
Breastfeeding Likely Safe When the tomato fruit or its products are consumed in typical food amounts. There is insufficient reliable information available about the safety of tomato extr... 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 Metformin and Tomato? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Tomato and Metformin 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.

  • Dizziness / Headache Additional detail

    Tomato

    “Orally, the glycoalkaloid tomatine in tomato leaf or green tomatoes can cause dizziness, stupor, headache, and mild spasms when consumed in excessive amounts (18,102957).”

    Tomato · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 102957. Friedman M. Tomato Glycoalkaloids: Role in the Plant and in the Diet. J Agric Food Chem. 2002;50(21):5751-80. PubMed

    Metformin

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

  • Diarrhea / Vomiting Additional detail

    Tomato

    “Orally, tomato leaves and ripe or unripe tomato fruit are well tolerated in typical food amounts. Tomato extracts also seem to be well tolerated. Tomatine, a glycoalkaloid found in tomato leaves and unripe green tomatoes, can cause serious side effects when consumed in excessive amounts.

    Serious Adverse Effects (Rare):

    Orally: Bradycardia, diarrhea, respiratory disturbances, spasms, vomiting, and death with excessive…”

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

    “Orally, the glycoalkaloid tomatine in tomato leaf or green tomatoes can cause severe mucous membrane irritation, vomiting, diarrhea, and colic when consumed in excessive amounts (18,102957).”

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

    2 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 102957. Friedman M. Tomato Glycoalkaloids: Role in the Plant and in the Diet. J Agric Food Chem. 2002;50(21):5751-80. PubMed

    Metformin

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

Reported for Tomato but not commonly for Metformin: a slow heartbeat.

Effects for Metformin come from the ADVERSE REACTIONS section of its FDA label; effects for Tomato 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.

Special populations

Tomato in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When the tomato fruit or its products are consumed in typical food amounts. There is insufficient reliable information available about the safety of tomato extracts when used during pregnancy or lactation; 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

Overlapping uses

What Metformin Is Prescribed For, and What Tomato Has Been Studied For

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

Metformin is prescribed for: Metformin is used to improve blood sugar (glucose) control in people with type 2 diabetes mellitus. It is always used together with diet and exercise, not instead of them. Metformin hydrochloride tablets and oral solution are approved for adults and children 10 years and older. Metformin hydrochloride extended-release tablets — including brands such as Fortamet, Glumetza, and Metformin Hydrochloride Extended Release — are approved for adults only.

Tomato has been studied for:

  • Diabetes studied, not established Tomato has been studied for this. Natural Medicines rates the evidence: Possibly Ineffective Read what the research shows

    Tomato for diabetes

    Consuming tomatoes and tomato-based products does not appear to prevent the development of type 2 diabetes or improve glycemic control in patients with type 2 diabetes.

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 Metformin on your own; if you are taking Tomato for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Tomato or Metformin

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

This page covers Tomato only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin page lists 258 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate) and Agaricus Mushroom (moderate).

By severity: 2 major · 217 moderate · 39 minor.

From our pharmacist’s overview on the Metformin page

“Siberian cocklebur is the ingredient I most want anyone taking metformin (Glucophage) to know about. It has caused severe low blood sugar in people, documented in humans, and it should not be combined with any glucose-lowering medication.”

Reviewed by 2 · Jul 18, 2026

Open the Metformin interaction page

One more smart check

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

We hold 2,820 real supplement products containing Tomato, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Tomato. Even though Tomato itself has no known interaction with Metformin, 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 Tomato and Metformin 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 Tomato
Top 10%

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

29 days ago today
Medication Metformin
Top 1%

#29 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 Tomato reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Tomato and Metformin 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 Tomato

What is Tomato?

  • Heart health support
  • Prostate health
  • Antioxidant support
  • Skin protection from sun damage
  • General nutrition

Tomato is a common food rich in vitamins, potassium, and the antioxidant lycopene, and eating it as part of a balanced diet is healthy for most people. Concentrated tomato or lycopene supplements are marketed for heart and prostate health, but the evidence is mixed and far from proven. Talk to your pharmacist or doctor before using high-dose supplements, especially if you are pregnant or have a medical condition.

Solanum lycopersicum · Solanaceae · Fruit (and extracts such as lycopene from the fruit and skin) · Whole fruit, juice, paste, tomato extract capsules, lycopene supplements

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

Tomato: dosing

There is no official standardized dose of tomato or lycopene supplements, and a proven effective amount has not been established. Tomatoes are best enjoyed simply as part of a balanced diet.If you choose to use a tomato extract or lycopene supplement, follow the directions on the product label and do not exceed the recommended amount.

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

Read the full Tomato monograph & all interactions
Medication

About Metformin

What Is Metformin Used For?

Brand names: Glucophage, Metformin

Metformin is used to improve blood sugar (glucose) control in people with type 2 diabetes mellitus. It is always used together with diet and exercise, not instead of them.

Metformin hydrochloride tablets and oral solution are approved for adults and children 10 years and older. Metformin hydrochloride extended-release tablets — including brands such as Fortamet, Glumetza, and Metformin Hydrochloride Extended Release — are approved for adults only.

See full Metformin drug information
Keep checking

Other Drugs & Tomato

Browse every other medication we’ve checked against Tomato — 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 Tomato 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 Tomato list.

See the full Tomato interactions page
See every supplement checked against Metformin, ranked by severity
Evidence & sources

Tomato References

The 3 references that drive our Tomato 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. Asero R, Mistrello G, Amato S. Airborne allergy to tomato proteins. Allergy. 2010;65(12):1626-7. PubMed
  3. Friedman M. Tomato Glycoalkaloids: Role in the Plant and in the Diet. J Agric Food Chem. 2002;50(21):5751-80. PubMed

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 Tomato and Metformin Together: Common Questions

Is it safe to take Tomato with Metformin?
We do not list a known interaction between Tomato and Metformin. 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 Tomato and Metformin have any of the same side effects?
Yes — our sources link each of them separately to 4 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 Tomato and Metformin 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 Tomato in each. That is a conversation for your prescriber, especially if Metformin is being adjusted to a target.
Does Metformin interact with any supplements?
Yes. Metformin has documented interactions with 258 supplements in our database — Tomato is not one of them. The Metformin 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

Tomato monograph Uses, safety profile, and every drug interaction in one place Metformin drug information The full plain-English guide to this medication Metformin supplement interactions Every supplement checked against Metformin, 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 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Metformin and Tomato?

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.