Drug & supplement interaction

Yellow Toadflax + Metronidazole

Metronidazole brand names: Flagyl, Protostat, Metronidazole, Nidazol, Trikacide, and others.

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

We found no known interaction between Yellow Toadflax and Metronidazole 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.

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Interaction report

Yellow Toadflax and Metronidazole

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 Metronidazole and Yellow Toadflax 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 Yellow Toadflax at all — not against Metronidazole, 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.

Yellow Toadflax safety at a glance

Yellow Toadflax overall Use caution Modern safety data are very limited, so use cautiously and only short-term.
Pregnancy Avoid Not enough safety information; avoid use during pregnancy.
Breastfeeding Avoid No reliable safety data, so avoid while breastfeeding.

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

Still wondering about combining Metronidazole and Yellow Toadflax? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Metronidazole’s Own FDA Label Lists

This is not an interaction — none of it involves Yellow Toadflax. These are the most notable effects listed in the ADVERSE REACTIONS section of Metronidazole’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

  • Hearing loss Worth acting on
  • Pain or burning when passing urine Worth acting on
  • Unsteadiness Worth acting on
  • Pancreatitis Worth acting on
  • Fainting Worth acting on
  • An irregular heartbeat Worth acting on
  • Confusion Worth acting on
  • A severe skin reaction Worth acting on
  • Seizures Worth acting on
  • Low mood Worth acting on

Showing the 10 most notable of 35 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Metronidazole. Read the label on DailyMed › Where a percentage is shown, it is the share of 64,630 voluntary FDA FAERS reports for Metronidazole that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Yellow Toadflax’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Yellow Toadflax side to compare — that is a limit of the record, not a statement that Yellow Toadflax has no side effects.

From our Q&A

Questions About Yellow Toadflax or Metronidazole

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

This page covers Yellow Toadflax only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metronidazole page lists 83 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 7 major · 63 moderate · 13 minor.

From our pharmacist’s overview on the Metronidazole page

“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 ch…”

Reviewed by 2 · Jul 18, 2026

Open the Metronidazole interaction page

How much people look this up

Where Yellow Toadflax and Metronidazole 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 Yellow Toadflax
Steady interest

#1,274 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Metronidazole
Top 25%

#633 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. Yellow Toadflax is not yet covered by that licensed database, so its write-up cites publicly available medical sources directly (see the references below).
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Yellow Toadflax reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Yellow Toadflax and Metronidazole records this page draws on were last updated June 22, 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 Yellow Toadflax

What is Yellow Toadflax?

  • Hemorrhoids and skin irritation
  • Mild constipation
  • Fluid retention (as a folk diuretic)
  • Liver and gallbladder complaints (traditional)
  • Minor wounds and inflammation (topical)

Yellow toadflax is a traditional folk remedy used mostly for hemorrhoids, skin problems, and as a mild laxative or diuretic, but there is very little modern human research to confirm any of these uses. Because its safety has not been well studied, it is best used cautiously, avoided in pregnancy and breastfeeding, and discussed with a pharmacist or doctor first.

Linaria vulgaris · Plantaginaceae · Aerial parts (flowering tops, leaves, and stems) · Tea, tincture, dried herb, ointment or salve, poultice

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

Yellow Toadflax: dosing

There is no well-established or standardized dose for yellow toadflax. Traditional preparations vary widely, and modern guidelines for safe amounts do not exist.If you choose to use a commercial product, follow the directions on the label and do not exceed them.

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

Read the full Yellow Toadflax monograph & all interactions
Medication

About Metronidazole

What Is Metronidazole Used For?

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

Metronidazole treats three main types of infections. It's used for trichomoniasis (a sexually transmitted parasitic infection), amebiasis (an intestinal or liver infection caused by a parasite), and serious anaerobic bacterial infections — infections caused by bacteria that thrive without oxygen, which can affect the abdomen, skin, bones, lungs, and other areas.

Because sexual partners can pass trichomoniasis back and forth, both partners are typically treated at the same time, even if one has no symptoms.

Most-Reported Side Effects for Metronidazole

From FAERS, the FDA’s public side-effect reporting system (64,630 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Nausea 4,812 reports
Diarrhea 4,197 reports
Vomiting 3,393 reports
Fever 3,294 reports
Drug hypersensitivity 3,160 reports
See full Metronidazole drug information
Keep checking

Other Drugs & Yellow Toadflax

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

See the full Yellow Toadflax interactions page
See every supplement checked against Metronidazole, ranked by severity
Evidence & sources

Yellow Toadflax References

The 1 sources that drive our Yellow Toadflax monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing. Yellow Toadflax is not covered by the licensed Natural Medicines interaction database, so its page cites these public sources directly.

  1. Dietary and Herbal Supplements — NIH NCCIH Source

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 Yellow Toadflax and Metronidazole Together: Common Questions

Is it safe to take Yellow Toadflax with Metronidazole?
We do not list a known interaction between Yellow Toadflax and Metronidazole. 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.
Does Metronidazole interact with any supplements?
Yes. Metronidazole has documented interactions with 83 supplements in our database — Yellow Toadflax is not one of them. The Metronidazole 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

Yellow Toadflax monograph Uses, safety profile, and every drug interaction in one place Metronidazole drug information The full plain-English guide to this medication Metronidazole supplement interactions Every supplement checked against Metronidazole, 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 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Metronidazole and Yellow Toadflax?

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.