Drug interactions
Fluconazole + Tolterodine
Severity: Moderate
Fluconazole and Tolterodine: 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
Fluconazole inhibits CYP3A4 and CYP2C9, and moderately inhibits CYP2C19, which can increase tolterodine exposure. The effect matters most in poor CYP2D6 metabolisers, in whom CYP3A4 carries the clearance. Higher levels raise the risk of anticholinergic effects and QT prolongation, and fluconazole itself can prolong QT.
What this interaction means in plain words
Fluconazole and Tolterodine 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.
Fluconazole belongs to Anti Fungals; Tolterodine belongs to Genitourinary.
Why it happens
Fluconazole inhibits CYP3A4 metabolism of tolterodine, with additive QT effects.
What to do
Monitor for anticholinergic effects and consider an ECG in patients with QT risk factors. Reduce the tolterodine dose in poor CYP2D6 metabolisers or when other inhibitors are present.
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 Tolterodine
Other interactions of Fluconazole
- Dihydroergotamine intranasal + Fluconazole Contraindicated
- Dihydroergotamine + Fluconazole Contraindicated
- Dofetilide + Fluconazole Contraindicated
- Domperidone + Fluconazole Contraindicated
- Dronedarone + Fluconazole Contraindicated
- Erythromycin + Fluconazole Contraindicated
Frequently asked questions
Can I take Fluconazole with Tolterodine?
MediHelp rates the interaction as moderate. Fluconazole and Tolterodine 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. Fluconazole inhibits CYP3A4 and CYP2C9, and moderately inhibits CYP2C19, which can increase tolterodine exposure. The effect matters most in poor CYP2D6 metabolisers, in whom CYP3A4 carries the clearance. Higher levels raise the risk of anticholinergic effects and QT prolongation, and fluconazole itself can prolong QT.
How serious is the interaction between Fluconazole and Tolterodine?
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 anticholinergic effects and consider an ECG in patients with QT risk factors. Reduce the tolterodine dose in poor CYP2D6 metabolisers or when other inhibitors are present.
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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