Drug interactions
Clarithromycin + Tolterodine
Severity: Major
Clarithromycin and Tolterodine: major 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
Clarithromycin is a strong CYP3A4 inhibitor and raises tolterodine exposure, particularly in CYP2D6 poor metabolizers. Increased levels may enhance anticholinergic effects and QT prolongation risk, and both drugs have QT liability.
What this interaction means in plain words
Clarithromycin and Tolterodine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Clarithromycin belongs to Anti Bacterial; Tolterodine belongs to Genitourinary.
Why it happens
Strong CYP3A4 inhibition by clarithromycin reduces tolterodine metabolism, with additive QT effects.
What to do
Limit tolterodine to 2 mg daily (1 mg twice daily for IR) during co-treatment, or use an alternative antibiotic such as azithromycin; monitor ECG in patients with QT risk factors.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Tolterodine
Other interactions of Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
Frequently asked questions
Can I take Clarithromycin with Tolterodine?
MediHelp rates the interaction as major. Clarithromycin and Tolterodine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Clarithromycin is a strong CYP3A4 inhibitor and raises tolterodine exposure, particularly in CYP2D6 poor metabolizers. Increased levels may enhance anticholinergic effects and QT prolongation risk, and both drugs have QT liability.
How serious is the interaction between Clarithromycin and Tolterodine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Limit tolterodine to 2 mg daily (1 mg twice daily for IR) during co-treatment, or use an alternative antibiotic such as azithromycin; monitor ECG in patients with QT risk factors.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clozapine, Cobicistat, Dronedarone. The full list is on the Tolterodine page.
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