Drug interactions
Estropipate + Phenytoin
Severity: Moderate
Estropipate 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
Phenytoin can lower estrogen concentrations, reducing the efficacy of estropipate. Contraceptive failure is possible if an estrogen is used for contraception.
What this interaction means in plain words
Estropipate 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
Phenytoin induces CYP3A4 and may increase P-glycoprotein efflux, lowering estrogen exposure.
What to do
Monitor symptom control and bleeding pattern and increase the estrogen dose if needed. Use a non-hormonal contraceptive if contraception 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 Estropipate with Phenytoin?
MediHelp rates the interaction as moderate. Estropipate 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. Phenytoin can lower estrogen concentrations, reducing the efficacy of estropipate. Contraceptive failure is possible if an estrogen is used for contraception.
How serious is the interaction between Estropipate 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: Monitor symptom control and bleeding pattern and increase the estrogen dose if needed. Use a non-hormonal contraceptive if contraception 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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