Drug interactions
Fosphenytoin + Sertraline
Severity: Moderate
Fosphenytoin and Sertraline: 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
Sertraline may raise phenytoin concentrations, and phenytoin has a narrow therapeutic index, so toxicity such as ataxia, nystagmus and confusion can occur. Case reports describe this, and phenytoin may also lower sertraline levels through enzyme induction.
What this interaction means in plain words
Fosphenytoin and Sertraline 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.
Fosphenytoin belongs to Central Nervous System; Sertraline belongs to Central Nervous System.
Why it happens
Sertraline may inhibit CYP2C9/CYP2C19 metabolism of phenytoin, while phenytoin may induce sertraline metabolism.
What to do
Measure phenytoin levels after starting or stopping sertraline and adjust the fosphenytoin dose accordingly. Monitor for neurotoxicity and for changes in antidepressant response.
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 Sertraline
- Isocarboxazid + Sertraline Contraindicated
- Methylene blue + Sertraline Contraindicated
- Phenelzine + Sertraline Contraindicated
- Pimozide + Sertraline Contraindicated
- Selegiline transdermal + Sertraline Contraindicated
- Selegiline + Sertraline Contraindicated
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Sertraline?
MediHelp rates the interaction as moderate. Fosphenytoin and Sertraline 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. Sertraline may raise phenytoin concentrations, and phenytoin has a narrow therapeutic index, so toxicity such as ataxia, nystagmus and confusion can occur. Case reports describe this, and phenytoin may also lower sertraline levels through enzyme induction.
How serious is the interaction between Fosphenytoin and Sertraline?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Measure phenytoin levels after starting or stopping sertraline and adjust the fosphenytoin dose accordingly. Monitor for neurotoxicity and for changes in antidepressant response.
What other medicines interact with Sertraline?
MediHelp also lists interactions of Sertraline with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Sertraline page.
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