Drug interactions
Diphenhydramine + Haloperidol
Severity: Moderate
Diphenhydramine 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
Diphenhydramine is a sedating, strongly anticholinergic antihistamine and a CYP2D6 inhibitor. Together with haloperidol it increases sedation and anticholinergic effects and may modestly raise haloperidol exposure.
What this interaction means in plain words
Diphenhydramine 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.
Diphenhydramine belongs to Respiratory; Haloperidol belongs to Central Nervous System.
Why it happens
Additive CNS depression and antimuscarinic effects, plus CYP2D6 inhibition by diphenhydramine reducing haloperidol clearance.
What to do
Monitor for oversedation, confusion and extrapyramidal symptoms, especially in older adults. Use the lowest effective doses and consider a non-sedating antihistamine.
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 Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Haloperidol?
MediHelp rates the interaction as moderate. Diphenhydramine 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. Diphenhydramine is a sedating, strongly anticholinergic antihistamine and a CYP2D6 inhibitor. Together with haloperidol it increases sedation and anticholinergic effects and may modestly raise haloperidol exposure.
How serious is the interaction between Diphenhydramine 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 for oversedation, confusion and extrapyramidal symptoms, especially in older adults. Use the lowest effective doses and consider a non-sedating antihistamine.
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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