Drug interactions
Oxcarbazepine + Phenytoin
Severity: Moderate
Oxcarbazepine 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
Oxcarbazepine can raise phenytoin concentrations, particularly at higher oxcarbazepine doses, resulting in phenytoin toxicity. Phenytoin can also lower the active oxcarbazepine metabolite.
What this interaction means in plain words
Oxcarbazepine 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.
Oxcarbazepine belongs to Central Nervous System; Phenytoin belongs to Central Nervous System.
Why it happens
Oxcarbazepine inhibits CYP2C19 and CYP2C9, reducing phenytoin metabolism, while phenytoin induces metabolism of the active monohydroxy derivative.
What to do
Monitor phenytoin levels and signs of toxicity during oxcarbazepine titration, and reduce the phenytoin dose if 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
Other interactions of Oxcarbazepine
- Cabotegravir + Oxcarbazepine Contraindicated
- Oxcarbazepine + Rilpivirine Contraindicated
- Artemether / lumefantrine + Oxcarbazepine Major
- Atazanavir + Oxcarbazepine Major
- Benzhydrocodone / acetaminophen + Oxcarbazepine Major
- Bictegravir + Oxcarbazepine Major
Frequently asked questions
Can I take Oxcarbazepine with Phenytoin?
MediHelp rates the interaction as moderate. Oxcarbazepine 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. Oxcarbazepine can raise phenytoin concentrations, particularly at higher oxcarbazepine doses, resulting in phenytoin toxicity. Phenytoin can also lower the active oxcarbazepine metabolite.
How serious is the interaction between Oxcarbazepine 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 phenytoin levels and signs of toxicity during oxcarbazepine titration, and reduce the phenytoin dose if 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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