Drug interactions
azithromycin + clarithromycin
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.
Overview
Additive QT prolongation with increased torsades de pointes risk when two macrolides are used together.
Mechanism of action
Pharmacodynamic: both macrolides block cardiac IKr (hERG) → prolonged repolarization/QT.
Clinical management
Avoid concurrent macrolide therapy; select an alternative without QT risk. If unavoidable, obtain baseline/follow-up ECG, correct K+/Mg2+, and monitor for palpitations/syncope.
Drug reference
References
- Azithromycin (Zithromax) Prescribing Information – Warnings: QT prolongation — FDA Label
- Clarithromycin (Biaxin) Prescribing Information – Warnings: QT prolongation and torsades de pointes — FDA Label
- QTdrugs Lists: Azithromycin; Clarithromycin – Known Risk of Torsades de Pointes — CredibleMeds
Frequently asked questions
Can I take azithromycin with clarithromycin?
The interaction is rated: Major. Additive QT prolongation with increased torsades de pointes risk when two macrolides are used together.
How serious is the interaction between azithromycin and clarithromycin?
The interaction is rated: Major. Evidence level: High.
How is the interaction between azithromycin and clarithromycin managed?
Avoid concurrent macrolide therapy; select an alternative without QT risk. If unavoidable, obtain baseline/follow-up ECG, correct K+/Mg2+, and monitor for palpitations/syncope.
Why do azithromycin and clarithromycin interact?
Pharmacodynamic: both macrolides block cardiac IKr (hERG) → prolonged repolarization/QT.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.