Drug interactions
Fosphenytoin + Haloperidol
Severity: Moderate
Fosphenytoin and Haloperidol: 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, the active form of fosphenytoin, induces hepatic enzymes and can lower haloperidol concentrations, potentially reducing antipsychotic control. Haloperidol may also alter phenytoin levels in some patients.
What this interaction means in plain words
Fosphenytoin and Haloperidol 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; Haloperidol belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 and other hepatic enzymes by phenytoin accelerates haloperidol metabolism.
What to do
Monitor psychiatric response and consider increasing the haloperidol dose. Check phenytoin levels and adjust after any change.
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 Haloperidol
- Dofetilide + Haloperidol Contraindicated
- Dronedarone + Haloperidol Contraindicated
- Haloperidol + Ibutilide Contraindicated
- Haloperidol + Levoketoconazole Contraindicated
- Haloperidol + Panobinostat Contraindicated
- Haloperidol + Pimozide 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 Haloperidol?
MediHelp rates the interaction as moderate. Fosphenytoin and Haloperidol 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, the active form of fosphenytoin, induces hepatic enzymes and can lower haloperidol concentrations, potentially reducing antipsychotic control. Haloperidol may also alter phenytoin levels in some patients.
How serious is the interaction between Fosphenytoin and Haloperidol?
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 psychiatric response and consider increasing the haloperidol dose. Check phenytoin levels and adjust after any change.
What other medicines interact with Haloperidol?
MediHelp also lists interactions of Haloperidol with, for example, Dofetilide, Dronedarone, Ibutilide. The full list is on the Haloperidol page.
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