Drug interactions
Diphenhydramine + Pimozide
Severity: Moderate
Diphenhydramine and Pimozide: 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 antihistamine with strong anticholinergic activity and CYP2D6 inhibition, and pimozide is partly cleared by CYP2D6. The combination may increase drowsiness and anticholinergic effects, and higher pimozide exposure could add to QT risk.
What this interaction means in plain words
Diphenhydramine and Pimozide 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; Pimozide belongs to Central Nervous System.
Why it happens
Additive CNS and anticholinergic effects, plus possible CYP2D6 inhibition by diphenhydramine raising pimozide levels.
What to do
Avoid regular use of diphenhydramine as a sleep aid with pimozide and choose a non-sedating antihistamine. Monitor for sedation, anticholinergic effects and QT-related symptoms if combined.
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 Pimozide
- Adagrasib + Pimozide Contraindicated
- Amiodarone + Pimozide Contraindicated
- Amisulpride + Pimozide Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amoxapine + Pimozide Contraindicated
- Anagrelide + Pimozide Contraindicated
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Pimozide?
MediHelp rates the interaction as moderate. Diphenhydramine and Pimozide 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 antihistamine with strong anticholinergic activity and CYP2D6 inhibition, and pimozide is partly cleared by CYP2D6. The combination may increase drowsiness and anticholinergic effects, and higher pimozide exposure could add to QT risk.
How serious is the interaction between Diphenhydramine and Pimozide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid regular use of diphenhydramine as a sleep aid with pimozide and choose a non-sedating antihistamine. Monitor for sedation, anticholinergic effects and QT-related symptoms if combined.
What other medicines interact with Pimozide?
MediHelp also lists interactions of Pimozide with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Pimozide page.
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