Drug interactions
Fluoxetine + Tolterodine
Severity: Minor
Fluoxetine and Tolterodine: minor 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
Fluoxetine strongly inhibits CYP2D6 and raises tolterodine concentrations, while the active metabolite is reduced. Studies showed the total active moiety changes little because CYP3A4 compensates, so the clinical effect is modest.
What this interaction means in plain words
Fluoxetine and Tolterodine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fluoxetine belongs to Central Nervous System; Tolterodine belongs to Genitourinary.
Why it happens
CYP2D6 inhibition by fluoxetine slows conversion of tolterodine to its 5-hydroxymethyl metabolite.
What to do
No routine dose change is required; monitor for anticholinergic effects and QT-related symptoms in at-risk patients.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Tolterodine
Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Frequently asked questions
Can I take Fluoxetine with Tolterodine?
MediHelp rates the interaction as minor. Fluoxetine and Tolterodine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Fluoxetine strongly inhibits CYP2D6 and raises tolterodine concentrations, while the active metabolite is reduced. Studies showed the total active moiety changes little because CYP3A4 compensates, so the clinical effect is modest.
How serious is the interaction between Fluoxetine and Tolterodine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine dose change is required; monitor for anticholinergic effects and QT-related symptoms in at-risk patients.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Cobicistat. The full list is on the Tolterodine page.
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