Darifenacin and Fesoterodine interaction
Darifenacin and Fesoterodine: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Darifenacin label · effective 2026-02-10
Darifenacin extended-release tablets, like other anticholinergic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as severe constipation, ulcerative colitis, and myasthenia gravis.
The concomitant use of darifenacin extended-release tablets with other anticholinergic agents may increase the frequency and/or severity of dry mouth, constipation, blurred vision and other anticholinergic pharmacological effects.
Other Anticholinergic Agents The concomitant use of darifenacin extended-release tablets with other anticholinergic agents may increase the frequency and/or severity of dry mouth, constipation, blurred vision and other anticholinergic pharmacological effects.
From the Fesoterodine (Toviaz) label · effective 2026-04-07
Urinary Retention in Adult Patients With Bladder Outlet Obstruction The use of Toviaz, like other antimuscarinic drugs, in patients with clinically significant bladder outlet obstruction, including patients with urinary retention, may result in further urinary retention and kidney injury.
Antimuscarinic Drugs Coadministration of Toviaz with other antimuscarinic agents that produce dry mouth, constipation, urinary retention, and other anticholinergic pharmacological effects may increase the frequency and/or severity of such effects.
In poor metabolizers for CYP2D6, representing a maximum CYP2D6 inhibition, C max and AUC of the active metabolite are increased 1.7- and 2-fold, respectively.
No dosing adjustments are recommended in the presence of CYP2D6 inhibitors.
CYP2D6 Inhibitors The interaction with CYP2D6 inhibitors was not tested clinically.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.