Drug interactions
Darifenacin + Trihexyphenidyl
Severity: Moderate
Darifenacin 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 block muscarinic receptors, so combined use increases the risk of dry mouth, constipation, urinary retention, blurred vision, tachycardia and confusion. Older patients are especially vulnerable to delirium and heat intolerance.
What this interaction means in plain words
Darifenacin 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.
Darifenacin belongs to Genitourinary; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive antimuscarinic pharmacodynamic effects.
What to do
Avoid combining where possible, especially in the elderly; if needed, use the lowest doses and monitor for constipation, urinary retention and cognitive changes.
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 Darifenacin
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Darifenacin with Trihexyphenidyl?
MediHelp rates the interaction as moderate. Darifenacin 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 block muscarinic receptors, so combined use increases the risk of dry mouth, constipation, urinary retention, blurred vision, tachycardia and confusion. Older patients are especially vulnerable to delirium and heat intolerance.
How serious is the interaction between Darifenacin 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 combining where possible, especially in the elderly; if needed, use the lowest doses and monitor for constipation, urinary retention and cognitive changes.
What other medicines interact with Darifenacin?
MediHelp also lists interactions of Darifenacin with, for example, Atazanavir, Bethanechol, Clarithromycin. The full list is on the Darifenacin page.
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