Drug interactions
Cortisone + Phenytoin
Severity: Moderate
Cortisone 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 metabolism of corticosteroids, which may reduce the effect of cortisone. Patients on replacement therapy could develop signs of under-replacement, and inflammatory conditions may flare.
What this interaction means in plain words
Cortisone 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 other enzymes, increasing corticosteroid clearance.
What to do
Monitor clinical response and increase the corticosteroid dose if needed; watch for adrenal insufficiency in replacement therapy.
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 Cortisone with Phenytoin?
MediHelp rates the interaction as moderate. Cortisone 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 metabolism of corticosteroids, which may reduce the effect of cortisone. Patients on replacement therapy could develop signs of under-replacement, and inflammatory conditions may flare.
How serious is the interaction between Cortisone 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 clinical response and increase the corticosteroid dose if needed; watch for adrenal insufficiency in replacement 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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