Dihydroergotamine and Metronidazole Topical: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Metronidazole Topical
Dihydroergotamine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased plasma concentrations of ergot derivatives and increased risk of ergotism (nausea, vomiting, vasospastic ischemia)
Interaction Deep Dive
Concomitant use of metronidazole, a CYP3A4 inhibitor, and an ergot derivative may result in increased plasma concentrations of the ergot derivative due to inhibition of CYP3A4-mediated ergot metabolism. Because of the potential for serious toxicity including vasospasm can occur, use caution with the concurrent use of metronidazole and ergot derivatives12.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated ergot metabolism by metronidazole
Common questions
Can I take Dihydroergotamine and Metronidazole Topical together?
Increased plasma concentrations of ergot derivatives and increased risk of ergotism (nausea, vomiting, vasospastic ischemia) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dihydroergotamine and Metronidazole Topical interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Dihydroergotamine or Metronidazole Topical need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Product Information: dihydroergotamine mesylate injection, dihydroergotamine mesylate injection. Paddock Laboratories,Inc, Minneapolis, MN, 2006. DailyMed
- Product Information: ERGOMAR(R) sublingual oral tablets, ergotamine tartrate sublingual oral tablets. Rosedale Therapeutics, Bristol, TN, 2003. DailyMed
Keep reading about Metronidazole Topical
Keep reading about Dihydroergotamine
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