Drug interactions
Risperidone + Trihexyphenidyl
Severity: Minor
Risperidone and Trihexyphenidyl: minor 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 commonly given with risperidone to treat extrapyramidal symptoms, which is beneficial. Risperidone has little anticholinergic activity, but the combination can still add anticholinergic effects such as confusion, constipation and dry mouth, especially in older adults.
What this interaction means in plain words
Risperidone and Trihexyphenidyl have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Risperidone belongs to Central Nervous System; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Trihexyphenidyl's anticholinergic action counteracts risperidone's dopamine blockade, and may add to peripheral and central anticholinergic burden.
What to do
Use the lowest effective trihexyphenidyl dose and review the need regularly. Monitor older patients for cognitive impairment, urinary retention and constipation.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Risperidone
- Ibutilide + Risperidone Contraindicated
- Risperidone + Vandetanib Contraindicated
- Adagrasib + Risperidone Major
- Amiodarone + Risperidone Major
- Amisulpride + Risperidone Major
- Amoxapine + Risperidone Major
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Risperidone with Trihexyphenidyl?
MediHelp rates the interaction as minor. Risperidone and Trihexyphenidyl have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Trihexyphenidyl is commonly given with risperidone to treat extrapyramidal symptoms, which is beneficial. Risperidone has little anticholinergic activity, but the combination can still add anticholinergic effects such as confusion, constipation and dry mouth, especially in older adults.
How serious is the interaction between Risperidone and Trihexyphenidyl?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use the lowest effective trihexyphenidyl dose and review the need regularly. Monitor older patients for cognitive impairment, urinary retention and constipation.
What other medicines interact with Risperidone?
MediHelp also lists interactions of Risperidone with, for example, Ibutilide, Vandetanib, Adagrasib. The full list is on the Risperidone page.
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