Drug interactions
Fesoterodine + OnabotulinumtoxinA
Severity: Moderate
Fesoterodine and OnabotulinumtoxinA: 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
Anticholinergic drugs may add to the effects of botulinum toxin, potentially increasing systemic anticholinergic effects or neuromuscular weakness. The risk is mainly theoretical with bladder injections, but urinary retention is more likely when the two are combined.
What this interaction means in plain words
Fesoterodine and OnabotulinumtoxinA 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; OnabotulinumtoxinA belongs to Musculoskeletal.
Why it happens
Additive cholinergic blockade: antimuscarinic receptor antagonism plus presynaptic inhibition of acetylcholine release.
What to do
Monitor for urinary retention, generalized weakness and swallowing or breathing difficulty after injection. Consider a post-injection residual urine check and adjust fesoterodine if retention develops.
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 Fesoterodine
Other interactions of OnabotulinumtoxinA
Frequently asked questions
Can I take Fesoterodine with OnabotulinumtoxinA?
MediHelp rates the interaction as moderate. Fesoterodine and OnabotulinumtoxinA 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. Anticholinergic drugs may add to the effects of botulinum toxin, potentially increasing systemic anticholinergic effects or neuromuscular weakness. The risk is mainly theoretical with bladder injections, but urinary retention is more likely when the two are combined.
How serious is the interaction between Fesoterodine and OnabotulinumtoxinA?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for urinary retention, generalized weakness and swallowing or breathing difficulty after injection. Consider a post-injection residual urine check and adjust fesoterodine if retention develops.
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.
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