Drug interactions
Orphenadrine + Trihexyphenidyl
Severity: Moderate
Orphenadrine 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
Orphenadrine has strong anticholinergic properties, so combining it with trihexyphenidyl significantly increases anticholinergic burden. This can cause confusion, agitation, hallucinations, tachycardia, urinary retention and constipation.
What this interaction means in plain words
Orphenadrine 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.
Why it happens
Additive central and peripheral muscarinic receptor antagonism.
What to do
Avoid routine duplication of anticholinergics; if both are needed, monitor cognition and autonomic effects and use the lowest doses, especially in older patients.
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 Trihexyphenidyl
Frequently asked questions
Can I take Orphenadrine with Trihexyphenidyl?
MediHelp rates the interaction as moderate. Orphenadrine 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. Orphenadrine has strong anticholinergic properties, so combining it with trihexyphenidyl significantly increases anticholinergic burden. This can cause confusion, agitation, hallucinations, tachycardia, urinary retention and constipation.
How serious is the interaction between Orphenadrine 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: Avoid routine duplication of anticholinergics; if both are needed, monitor cognition and autonomic effects and use the lowest doses, especially in older patients.
What other medicines interact with Trihexyphenidyl?
MediHelp also lists interactions of Trihexyphenidyl with, for example, Orphenadrin, Oxybutynin, Scopolamine. The full list is on the Trihexyphenidyl page.
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