Drug interactions
Haloperidol + Trihexyphenidyl
Severity: Moderate
Haloperidol and Trihexyphenidyl: 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
Trihexyphenidyl is often given to reduce haloperidol-induced extrapyramidal symptoms, but the combination adds anticholinergic burden. This can cause dry mouth, constipation, urinary retention, blurred vision, confusion, and heat intolerance, and may worsen psychosis or cognition.
What this interaction means in plain words
Haloperidol and Trihexyphenidyl 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.
Haloperidol belongs to Central Nervous System; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive antimuscarinic effects, with haloperidol's D2 blockade counteracted by central anticholinergic action.
What to do
Use trihexyphenidyl only when extrapyramidal symptoms occur and reassess the need regularly. Monitor for confusion, urinary retention, and constipation, especially in older adults.
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 Trihexyphenidyl
Frequently asked questions
Can I take Haloperidol with Trihexyphenidyl?
MediHelp rates the interaction as moderate. Haloperidol and Trihexyphenidyl 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. Trihexyphenidyl is often given to reduce haloperidol-induced extrapyramidal symptoms, but the combination adds anticholinergic burden. This can cause dry mouth, constipation, urinary retention, blurred vision, confusion, and heat intolerance, and may worsen psychosis or cognition.
How serious is the interaction between Haloperidol and Trihexyphenidyl?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use trihexyphenidyl only when extrapyramidal symptoms occur and reassess the need regularly. Monitor for confusion, urinary retention, and constipation, especially in older adults.
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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