Drug interactions
Fesoterodine + Trihexyphenidyl
Severity: Moderate
Fesoterodine 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 are potent antimuscarinics, so together they can cause marked dry mouth, constipation, urinary retention, blurred vision, confusion and heat intolerance. Older patients are especially vulnerable to delirium and ileus.
What this interaction means in plain words
Fesoterodine 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.
Fesoterodine belongs to Genitourinary; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive muscarinic receptor antagonism.
What to do
Avoid the combination in elderly patients where possible. Otherwise monitor for anticholinergic toxicity and reduce the dose of one agent if symptoms occur.
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 Fesoterodine 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 Fesoterodine
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Fesoterodine with Trihexyphenidyl?
MediHelp rates the interaction as moderate. Fesoterodine 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 are potent antimuscarinics, so together they can cause marked dry mouth, constipation, urinary retention, blurred vision, confusion and heat intolerance. Older patients are especially vulnerable to delirium and ileus.
How serious is the interaction between Fesoterodine 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 the combination in elderly patients where possible. Otherwise monitor for anticholinergic toxicity and reduce the dose of one agent if symptoms occur.
What other medicines interact with Fesoterodine?
MediHelp also lists interactions of Fesoterodine with, for example, Bethanechol, Clozapine, Levoketoconazole. The full list is on the Fesoterodine 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.
