Drug & supplement interaction

Alchemilla + Metronidazole

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

Minor Interaction
Medically reviewed by · Updated January 2024
The bottom line Minor

Alchemilla has a minor interaction with Metronidazole. While no side effects have been reported from orally using Alchemilla, a clinical study titled "Treatment of Aphthous Stomatitis with Topical Alchemilla vulgaris in Glycerine," published in Clinical Drug Investigation (https://pubmed.ncbi.nlm.nih.gov/17163290/), found that local mouth irritation occ...

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Alchemilla and Metronidazole

Here is the interaction we found between these two, with the evidence behind it.

Minor

Topical Drugs

Why this applies to Metronidazole

Metronidazole falls under Topical Drugs — the group Alchemilla interacts with.

While no side effects have been reported from orally using Alchemilla, a clinical study titled "Treatment of Aphthous Stomatitis with Topical Alchemilla vulgaris in Glycerine," published in Clinical Drug Investigation (https://pubmed.ncbi.nlm.nih.gov/17163290/), found that local mouth irritation occurred after applying a commercial product containing 3% alchemilla extract and glycerol (Aphtarine, Laboratoires Biosphere). Aphtarine was non-irritating in 68.2% of cases within 2-3 days, in 18.8% of cases within 4-7 days, and in 13.6% of cases with moderate irritation. Theoretically, combining Alchemilla with other potentially irritating topical products could increase the risk of local irritation and discomfort. The drug in this drug interaction monograph is available in a topical dosage form. There is no interaction expected from the oral dosage form of the drug.
Severity Minor Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the good news: this is a very mild, skin-level concern, and only if you're using a topical form of metronidazole like MetroGel on your face for rosacea. There's no expected problem with metronidazole capsules or tablets you swallow.

Alchemilla is high in tannins, which dry and tighten the skin and can be a little irritating on their own. If you apply an Alchemilla product on the same patch of skin as your metronidazole gel, the two together could add up to more redness, stinging, or dryness than either alone. This is theoretical and rated minor, so it's not dangerous. Still, if you want to use both, ask your pharmacist about spacing them out or whether to skip one.

Contact Dr. Brian directly if you have additional questions on this interaction

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Alchemilla Also Interacts With Other Medications

Alchemilla has 197 minor known drug interactions in our database — the Metronidazole one above is one of them. If you take anything else, check it against the full list below.

Minor 197 No known interaction 2,633 (incl. Metronidazole)
Taking anything else?

Check Another of Your Medications Against Alchemilla

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

From our Q&A

Questions About Alchemilla 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 Alchemilla 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 Alchemilla 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

One more smart check

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

We hold 19 real supplement products containing Alchemilla, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Alchemilla. Your product may carry other ingredients that interact with Metronidazole too, on top of Alchemilla — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Alchemilla 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 Alchemilla
Top half

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

29 days ago today
Medication Metronidazole
Top 25%

#632 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.

Supplement

About Alchemilla

What is Alchemilla?

Alchemilla
  • Menstrual and women's health complaints
  • Diarrhea and digestive upset
  • Wound healing (topical)
  • Skin moisturizing (topical)
  • Mild inflammation

Alchemilla (lady's mantle) is a European herb traditionally used for digestive complaints, women's health issues, and as an astringent for skin and wounds. Solid human research is very limited, so its benefits remain largely unproven, and it should be avoided in pregnancy and breastfeeding due to a lack of safety data.

Read the full Alchemilla 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.

See full Metronidazole drug information
Keep checking

Other Drugs & Alchemilla

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

0Major
0Moderate
197Minor
2,632No known interaction
197 Minor 2,632 No interaction
Minor

197 interactions

Showing 60 of 197 minor interactions — see all 197 on the Alchemilla page.

No interaction 2,632 drugs checked — show the list

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

Showing the 60 most looked-up of 2,632 medications checked with no known interaction — see the full Alchemilla list.

See the full Alchemilla interactions page
See every supplement checked against Metronidazole, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Alchemilla monograph › Uses, safety, and every drug interaction in one place Metronidazole supplement interactions › Every supplement checked against Metronidazole, ranked by severity Metronidazole drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Alchemilla and Metronidazole Together: Common Questions

Can you take Alchemilla with Metronidazole?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Alchemilla and Metronidazole interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Metronidazole and Alchemilla?

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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.