Drug interactions
Chlorpromazine + Trihexyphenidyl
Severity: Moderate
Chlorpromazine 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
Both drugs have anticholinergic activity, so the combination can cause dry mouth, constipation, urinary retention, blurred vision, confusion and heat intolerance. Trihexyphenidyl is often given to treat antipsychotic-induced parkinsonism, which makes the pairing common.
What this interaction means in plain words
Chlorpromazine 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.
Chlorpromazine belongs to Central Nervous System; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive antimuscarinic effects.
What to do
Use the anticholinergic only when needed for extrapyramidal symptoms, at the lowest dose, and monitor for cognitive and peripheral anticholinergic effects, particularly 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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Chlorpromazine and Trihexyphenidyl, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat Contraindicated
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Chlorpromazine with Trihexyphenidyl?
MediHelp rates the interaction as moderate. Chlorpromazine 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. Both drugs have anticholinergic activity, so the combination can cause dry mouth, constipation, urinary retention, blurred vision, confusion and heat intolerance. Trihexyphenidyl is often given to treat antipsychotic-induced parkinsonism, which makes the pairing common.
How serious is the interaction between Chlorpromazine 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 the anticholinergic only when needed for extrapyramidal symptoms, at the lowest dose, and monitor for cognitive and peripheral anticholinergic effects, particularly in older adults.
What other medicines interact with Chlorpromazine?
MediHelp also lists interactions of Chlorpromazine with, for example, Dofetilide, Dronedarone, Droperidol. The full list is on the Chlorpromazine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
