Drug interactions
Phenytoin + Prednisolone
Severity: Moderate
Phenytoin and Prednisolone: 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 CYP3A4 and other enzymes, accelerating prednisolone clearance and reducing its effect. Loss of disease control or inadequate steroid replacement may result.
What this interaction means in plain words
Phenytoin and Prednisolone 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 belongs to Central Nervous System; Prednisolone belongs to Endocrine.
Why it happens
Phenytoin induces hepatic CYP3A4 and P-glycoprotein, increasing prednisolone metabolism and clearance.
What to do
Monitor clinical response and increase the prednisolone dose if needed. Reassess the dose if phenytoin is stopped, as steroid exposure will rise.
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 Prednisolone
- Bcg vaccine live + Prednisolone Contraindicated
- Measles mumps and rubella vaccine live + Prednisolone Contraindicated
- Measles mumps rubella and varicella vaccine live + Prednisolone Contraindicated
- Measles vaccine + Prednisolone Contraindicated
- Mifepristone + Prednisolone Contraindicated
- Prednisolone + Radium-223 dichloride Contraindicated
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 Phenytoin with Prednisolone?
MediHelp rates the interaction as moderate. Phenytoin and Prednisolone 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 CYP3A4 and other enzymes, accelerating prednisolone clearance and reducing its effect. Loss of disease control or inadequate steroid replacement may result.
How serious is the interaction between Phenytoin and Prednisolone?
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 prednisolone dose if needed. Reassess the dose if phenytoin is stopped, as steroid exposure will rise.
What other medicines interact with Prednisolone?
MediHelp also lists interactions of Prednisolone with, for example, Bcg vaccine live, Measles mumps and rubella vaccine live, Measles mumps rubella and varicella vaccine live. The full list is on the Prednisolone page.
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