Drug interactions
Nefazodone + Phenytoin
Severity: Moderate
Nefazodone 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 CYP3A4 and can markedly lower nefazodone and its active metabolite levels, possibly causing loss of antidepressant effect. Nefazodone is a CYP3A4 inhibitor and may also increase phenytoin levels.
What this interaction means in plain words
Nefazodone 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-mediated nefazodone metabolism, while nefazodone inhibits CYP3A4.
What to do
Monitor antidepressant response and consider an alternative antidepressant if effect is lost. Monitor phenytoin levels when nefazodone is 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
Frequently asked questions
Can I take Nefazodone with Phenytoin?
MediHelp rates the interaction as moderate. Nefazodone 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 CYP3A4 and can markedly lower nefazodone and its active metabolite levels, possibly causing loss of antidepressant effect. Nefazodone is a CYP3A4 inhibitor and may also increase phenytoin levels.
How serious is the interaction between Nefazodone 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 antidepressant response and consider an alternative antidepressant if effect is lost. Monitor phenytoin levels when nefazodone is 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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