Drug interactions
Miconazole vaginal + Phenytoin
Severity: Moderate
Miconazole vaginal and Phenytoin: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Miconazole is a CYP2C9 inhibitor, and even vaginal use can lead to some systemic absorption. This may raise phenytoin concentrations and cause toxicity, as has been reported with miconazole.
What this interaction means in plain words
Miconazole vaginal and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Miconazole inhibits CYP2C9 and CYP2C19, reducing phenytoin metabolism.
What to do
Watch for signs of phenytoin toxicity such as nystagmus, ataxia and confusion during and after treatment. Measure phenytoin levels if symptoms arise or if prolonged treatment is needed.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Miconazole vaginal with Phenytoin?
MediHelp rates the interaction as moderate. Miconazole vaginal and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Miconazole is a CYP2C9 inhibitor, and even vaginal use can lead to some systemic absorption. This may raise phenytoin concentrations and cause toxicity, as has been reported with miconazole.
How serious is the interaction between Miconazole vaginal and Phenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Watch for signs of phenytoin toxicity such as nystagmus, ataxia and confusion during and after treatment. Measure phenytoin levels if symptoms arise or if prolonged treatment is needed.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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