Drug interactions
Medroxyprogesterone + Phenytoin
Severity: Moderate
Medroxyprogesterone 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 induces hepatic enzymes and can speed up the metabolism of progestins, lowering medroxyprogesterone exposure. With contraceptive use this may lead to contraceptive failure and unintended pregnancy.
What this interaction means in plain words
Medroxyprogesterone 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.
Medroxyprogesterone belongs to Endocrine; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing the clearance of medroxyprogesterone.
What to do
Counsel patients using medroxyprogesterone for contraception about possible reduced efficacy and consider an additional or alternative non-hormonal method. Review the contraceptive plan whenever enzyme-inducing antiepileptics are started or stopped.
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
Other interactions of Medroxyprogesterone
Frequently asked questions
Can I take Medroxyprogesterone with Phenytoin?
MediHelp rates the interaction as moderate. Medroxyprogesterone 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 induces hepatic enzymes and can speed up the metabolism of progestins, lowering medroxyprogesterone exposure. With contraceptive use this may lead to contraceptive failure and unintended pregnancy.
How serious is the interaction between Medroxyprogesterone 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: Counsel patients using medroxyprogesterone for contraception about possible reduced efficacy and consider an additional or alternative non-hormonal method. Review the contraceptive plan whenever enzyme-inducing antiepileptics are started or stopped.
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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