ModerateMacrolides×Selective serotonin reuptake inhibitors
Updated · Methodology
Mechanism
Additive QT prolongation (fluoxetine weakly prolongs QT at high doses).
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
For short azithromycin courses (3–5 days) with normal potassium and magnesium, the combination is acceptable. In cardiovascular disease or fluoxetine doses above 40 mg: ECG before start or alternative antibiotics (doxycycline, a cephalosporin).
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Zithromax (azithromycin) prescribing information (2013)– ; DailyMed setid db52b91e-79f7-4cc1-9564-f2eee8e31c45
- AEMPS: Ficha técnica: Fluoxetina (nº registro 63499), sección 4.5 (2026)– AEMPS, CIMA, nº registro 63499, revisión 10/2026, sección 4.5