Drug interactions
Citalopram + Fosphenytoin
Severity: Moderate
Citalopram and Fosphenytoin: 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
Fosphenytoin (converted to phenytoin) induces hepatic enzymes and may lower citalopram plasma concentrations. This could reduce antidepressant effect over time.
What this interaction means in plain words
Citalopram and Fosphenytoin 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.
Citalopram belongs to Central Nervous System; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and CYP2C19, which increases the metabolism of citalopram.
What to do
Monitor for loss of antidepressant response and increase the citalopram dose if needed within the labeled maximum. Also watch phenytoin levels when citalopram 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 Citalopram
- Cisapride + Citalopram Contraindicated
- Citalopram + Dronedarone Contraindicated
- Citalopram + Escitalopram Contraindicated
- Citalopram + Isocarboxazid Contraindicated
- Citalopram + Methylene blue Contraindicated
- Citalopram + Phenelzine 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 Citalopram with Fosphenytoin?
MediHelp rates the interaction as moderate. Citalopram and Fosphenytoin 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 (converted to phenytoin) induces hepatic enzymes and may lower citalopram plasma concentrations. This could reduce antidepressant effect over time.
How serious is the interaction between Citalopram and Fosphenytoin?
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 for loss of antidepressant response and increase the citalopram dose if needed within the labeled maximum. Also watch phenytoin levels when citalopram is started or stopped.
What other medicines interact with Citalopram?
MediHelp also lists interactions of Citalopram with, for example, Cisapride, Dronedarone, Escitalopram. The full list is on the Citalopram page.
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