Medication interaction hub

What Supplements Interact with Metronidazole?

Metronidazole brand names: Flagyl, Protostat, Metronidazole, Nidazol, Trikacide, and others. Every interaction below applies to the brands too.

83 Interactions 7 Major 63 Moderate 13 Minor
Curated & coded by · Clinical Pharmacist · Updated September 22, 2026

Drug–supplement interaction data sourced from Natural Medicines Pro, the licensed clinical database from TRC Healthcare / Therapeutic Research, with additional analysis by the HelloPharmacist Pharmacist Team. Our sources · Editorial policy

What is this page for?

One answer, for one medication: what supplements and herbal products interact with Metronidazole? Every vitamin, herb, and supplement ingredient we’ve checked against it is on this page, ranked by severity, each linking to the full report for that exact pair.

This page covers supplement interactions only — to check Metronidazole against your other medications, use the drug–drug interaction checker. Educational information from our licensed clinical databases, not medical advice. Our editorial policy

HelloPharmacist Bottom Line
Our Pharmacist Explains
What is this? The interaction data in the HelloPharmacist supplement database is licensed from Natural Medicines Pro by TRC Healthcare (Therapeutic Research). HelloPharmacist pharmacists often add our own analysis and context on top of that licensed data — such as this Bottom Line summary and the notes on individual interaction pages — and any such commentary is noted as ours.

Metronidazole (Flagyl) can stretch the heart's QT interval on its own, and most of the seven major-rated interactions among its 83 flagged supplement ingredients do the same thing, so I read this list with more wariness than most antibiotics earn. Grapefruit and ephedra stand out for adding to that heart-rhythm risk, while activated charcoal draws another major rating by soaking up the drug before it can do its job.

The 63 moderate and 13 minor entries are less dramatic. Roughly a third of the full list is probiotics, which an antibiotic like metronidazole can simply kill off, so space those well apart from your doses rather than dropping them. One quieter trap is Bach flower remedies, preserved in brandy, because metronidazole mixed with any alcohol can bring on flushing, nausea, and a racing heart.

— , Clinical Pharmacist · July 18, 2026

Major 7 Moderate 63 Minor 13 No known interaction 1,369

This box checks one ingredient at a time (like turmeric or magnesium). Taking a supplement product with a whole label of ingredients? Search the product instead — we check every ingredient on it ↓

Most Viewed Ingredient Interactions

Metronidazole: Top Interactions at a Glance

The Metronidazole supplement & herbal interactions people checked most in the last 24 hours, colored by severity. Tap any ingredient to open the full report for that pair.

Showing the 12 highest-ranked of 83 interacting ingredients — plus 1,369 more checked with no known interaction. See the complete ranked list.

Start here

The Most-Checked Metronidazole Combinations Today

The Metronidazole + supplement pages people viewed most in the last 24 hours (resets at midnight). Open any card for the full report.

Moderate Likelihood Probable Probiotics + Metronidazolei

Theoretically, taking antibiotic drugs with certain probiotics might decrease the effectiveness of probiotics.

Read the full interaction Moderate Likelihood Possible Cannabis + Metronidazolei

Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of cannabis.

Read the full interaction Major Likelihood Probable Grapefruit + Metronidazolei

Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT interval-prolonging drug...

Read the full interaction Major Likelihood Probable Activated Charcoal + Metronidazolei

Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.

Read the full interaction Moderate Likelihood Probable Bacillus Coagulans + Metronidazolei

Theoretically, taking antibiotics with Bacillus coagulans might decrease the effectiveness of B.

Read the full interaction Moderate Likelihood Possible Wine + Metronidazolei

Concomitant use may cause a disulfiram-like reaction.

Read the full interaction
The complete list

Every Supplement Checked Against Metronidazole

All 1,452 ingredients in our database, ranked by severity — 83 with a Metronidazole interaction on file and 1,369 with none found. Filter by severity or search any ingredient; hover the for what each ingredient is.

Looking for an interaction with a specific supplement product? Search products instead ↓

Straight answers

Can You Take It With Metronidazole?

One-line answers, one card per combination — scroll through today’s 20 and tap any card for the full report. A different set rotates in daily until every combination has had its turn.

Can you take Probiotics with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, taking antibiotic drugs with certain probiotics might decrease the effectiveness of probiotics.

Full Probiotics + Metronidazole answer

Can you take Cannabis with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of cannabis.

Full Cannabis + Metronidazole answer

Can you take Grapefruit with Metronidazole?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT inte...

Full Grapefruit + Metronidazole answer

Can you take Activated Charcoal with Metronidazole?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the rout...

Full Activated Charcoal + Metronidazole answer

Can you take Bacillus Coagulans with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, taking antibiotics with Bacillus coagulans might decrease the effectiveness of B.

Full Bacillus Coagulans + Metronidazole answer

Can you take Thunder God Vine with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of thunder god vine constituents.

Full Thunder God Vine + Metronidazole answer

Can you take Tragacanth with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, tragacanth might alter absorption of oral drugs.

Full Tragacanth + Metronidazole answer

Can you take Turpentine Oil with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Some in vitro research shows that alpha-pinene, the major constituent of turpentine oil, does not increase the absorption of chlorpromazine...

Full Turpentine Oil + Metronidazole answer

Can you take Wine with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Concomitant use may cause a disulfiram-like reaction.

Full Wine + Metronidazole answer

Can you take Yohimbe with Metronidazole?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, CYP3A4 inhibitors might increase the levels and adverse effects of yohimbine, a constituent of yohimbe bark.

Full Yohimbe + Metronidazole answer

Can you take Thyroid Extract with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Food and medications can interfere with thyroid hormone absorption.

Full Thyroid Extract + Metronidazole answer

Can you take Agar with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Agar forms a thick gel, which may disrupt the absorption of nutrients and medications.

Full Agar + Metronidazole answer

Can you take Alchemilla with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. While no side effects have been reported from orally using Alchemilla, a clinical study titled "Treatment of Aphthous Stomatitis with Topica...

Full Alchemilla + Metronidazole answer

Can you take Algin with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, algin can alter the absorption of oral drugs.

Full Algin + Metronidazole answer

Can you take Black Psyllium with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, psyllium might increase, decrease, or have no effect on the absorption of oral drugs.

Full Black Psyllium + Metronidazole answer

Can you take Blond Psyllium with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, psyllium might increase, decrease, or have no effect on the absorption of oral drugs.

Full Blond Psyllium + Metronidazole answer

Can you take Carob with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, carob might also impair the absorption of oral drugs.

Full Carob + Metronidazole answer

Can you take Ginger with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, ginger might increase levels of metronidazole.

Full Ginger + Metronidazole answer

Can you take Karaya Gum with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Co-administration of oral drugs with bulk forming laxatives such as karaya gum may decrease, increase, or have no effect on the absorption o...

Full Karaya Gum + Metronidazole answer

Can you take Marshmallow with Metronidazole?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, mucilage in marshmallow might impair absorption of oral drugs.

Full Marshmallow + Metronidazole answer
Read the list like a pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each entry links to a full report with the clinical detail, likelihood, evidence level, and citations for that exact combination.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

How Does Our Interaction Checker Work?

Behind every verdict on this page is a category system. Our source database doesn’t document supplement interactions drug-by-drug — it documents them against groups of medications that behave the same way (for example, “drugs processed by the CYP3A4 liver enzyme” or “blood-thinning medications”).

So the check works in three steps: (1) Metronidazole is classified into the pharmacology categories it belongs to, (2) every supplement interaction documented against any of those categories is inherited by Metronidazole, and (3) each ingredient keeps its own severity, likelihood, and evidence grades from the underlying record. That’s why one supplement can carry several records for one drug — it may interact through more than one category.

Metronidazole sits in 8 interaction categories. Open any one to see what the group means:

Antibiotic Drugs 27 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

27 of the supplement ingredients on this page reach Metronidazole through this category.

Oral Drugs 17 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

17 of the supplement ingredients on this page reach Metronidazole through this category.

Cytochrome P450 3A4 (Cyp3A4) Inhibitors 13 ingredients

A drug-metabolism group: these medications are processed by the named liver enzyme (a cytochrome P450). Supplements that speed this enzyme up or slow it down can lower or raise the medication's levels in your body.

13 of the supplement ingredients on this page reach Metronidazole through this category.

Qt Interval-Prolonging Drugs 13 ingredients

Medications that can affect the heart's electrical rhythm (the QT interval). Supplements with similar effects can add to that risk.

13 of the supplement ingredients on this page reach Metronidazole through this category.

Seizure Threshold Lowering Drugs 6 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

6 of the supplement ingredients on this page reach Metronidazole through this category.

Cytochrome P450 2C9 (Cyp2C9) Inhibitors 4 ingredients

A drug-metabolism group: these medications are processed by the named liver enzyme (a cytochrome P450). Supplements that speed this enzyme up or slow it down can lower or raise the medication's levels in your body.

4 of the supplement ingredients on this page reach Metronidazole through this category.

Metronidazole (Flagyl) 4 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

4 of the supplement ingredients on this page reach Metronidazole through this category.

Topical Drugs 3 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

3 of the supplement ingredients on this page reach Metronidazole through this category.

About Metronidazole

Metronidazole is an antibiotic used to treat bacterial and parasitic infections in various parts of the body, including the reproductive and gastrointestinal systems.

Generic name: Metronidazole  ·  Brand names: Flagyl, Protostat, Metronidazole, Nidazol, Trikacide, MetroGel, Flagyl IV, Metronidazole Redi-Infusion, Flagyl IV RTU, Metro IV, Anabact, Metrosa, Metrotop, Noritate, Rozex Cream, Rozex Gel, Zyomet, Likmez.

See the full Metronidazole drug information

Related: does Metronidazole deplete any nutrients?

Metronidazole has 70 reported nutrient associations in the research literature — see the Metronidazole nutrient depletion report.

Check a real product

Take a Supplement Product? Check the Whole Bottle Against Metronidazole

Most supplements are combination products — and the interaction may come from an ingredient you didn’t buy it for. Search any product below (or scan its label) and we’ll check every ingredient on it against Metronidazole.

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Pharmacist Counseling Corner

Metronidazole & Supplements: Common Questions

What supplements interact with Metronidazole?
In our interaction database, 83 supplement and herbal ingredients have an interaction with Metronidazole on file — 7 rated major, 63 moderate, and 13 minor. That number sounds scarier than it is: severity matters far more than the count, which is why the list on this page is ranked instead of alphabetical. Start at the top. The highest-ranked right now: Activated Charcoal, Arsenic, Cesium.
Which Metronidazole supplement interactions are the most serious?
The 7 major-rated combinations — led by Activated Charcoal, Arsenic, Cesium, Ephedra and Grapefruit — deserve real caution: these are the ones generally best avoided, or used only with your prescriber watching. If you take any of them today, don't panic and don't stop anything abruptly — call your pharmacist first. Jump to the ranked list.
Can I take vitamins or supplements while on Metronidazole?
That depends entirely on which supplement. The honest answer for Metronidazole is in the ranked list above — and if what you take is a combination product with a dozen ingredients, don't check them one by one: photograph the label with our scanner and we'll check the whole thing at once. Try the label scanner or the interaction checker.
Do brands like Flagyl have the same supplement interactions as Metronidazole?
Yes — Flagyl, Protostat, Metronidazole, Nidazol, Trikacide and other brands all contain Metronidazole, so everything on this page applies to them equally. Interactions belong to the active drug, never to the brand on the box; the same is true of generics.
Where do these interaction ratings come from?
Every rating comes from the Natural Medicines database — the same evidence-graded reference pharmacists and hospitals use — and each interaction carries three separate grades: severity (how bad it can be), likelihood (how well it's documented in studies and case reports), and an evidence level. Our pharmacists review the content; we never let an AI decide an interaction. See how to read the ratings and our editorial policy.
Does Metronidazole deplete any vitamins or nutrients?
It might — Metronidazole has 70 reported nutrient-depletion associations in the research literature, which is a different question from interactions: instead of a supplement changing the drug, the drug may lower a nutrient over time. See the Metronidazole nutrient depletion report for the specifics and what to discuss with your pharmacist.
What about Metronidazole and my other medications?
This page covers Metronidazole against supplements and herbal ingredients. Checking Metronidazole against your other prescription or OTC medications is a different tool — our drug interaction checker covers that side. Head to the drug–drug interaction checker, or read the full Metronidazole drug information.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Sourcing

Where This Data Comes From — and Why You Can Trust It

🧪 Licensed clinical database

Every interaction verdict on this page comes from Natural Medicines Pro (TRC Healthcare / Therapeutic Research) — the same evidence-graded reference used by pharmacists and hospitals. We license this data directly; we do not scrape it, and no AI invents an interaction.

🧑‍⚕️ Pharmacist review

This page is curated and coded by , Clinical Pharmacist, with additional analysis by the HelloPharmacist Pharmacist Team. Editorial commentary is ours; the licensed interaction records are shown as sourced.

🔄 Kept current

Our interaction database refreshes on a weekly cycle, and this page re-checks the live database every time it’s rebuilt — what you see reflects the database as of September 22, 2026.

🔍 Full transparency

How every dataset on this site is sourced, licensed, and updated is documented publicly: our data sources · editorial policy · how we use AI.

Educational information, not medical advice. An interaction being on file does not mean it will happen to you — and absence of one is not proof of safety. Never start or stop a medication or supplement without talking to your pharmacist or doctor.