Drug interactions
Estradiol vaginal + Phenytoin
Severity: Minor
Estradiol vaginal and Phenytoin: minor 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
Phenytoin is an enzyme inducer and may lower systemic estradiol exposure. With low-dose vaginal products the systemic effect is small, but reduced estrogen effect is possible, especially with systemic absorption from higher-dose preparations.
What this interaction means in plain words
Estradiol vaginal and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Phenytoin induces CYP3A4, increasing estradiol metabolism.
What to do
Monitor for recurrence of menopausal symptoms and increase the estrogen dose if needed. No routine adjustment is needed for low-dose local therapy.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Estradiol vaginal with Phenytoin?
MediHelp rates the interaction as minor. Estradiol vaginal and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenytoin is an enzyme inducer and may lower systemic estradiol exposure. With low-dose vaginal products the systemic effect is small, but reduced estrogen effect is possible, especially with systemic absorption from higher-dose preparations.
How serious is the interaction between Estradiol vaginal and Phenytoin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for recurrence of menopausal symptoms and increase the estrogen dose if needed. No routine adjustment is needed for low-dose local therapy.
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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