Azithromycin × Ciprofloxacin

Both antibiotics prolong the QT interval on the electrocardiogram, and taken together they raise the risk of arrhythmias, including torsades de pointes (azithromycin and ciprofloxacin SmPCs).

QT prolongation on the electrocardiogram (ECG), palpitations, dizziness, fainting. Rarely, torsades de pointes, which can lead to cardiac arrest (azithromycin SmPC). The risk is higher in older patients and women, with hypokalaemia or hypomagnesaemia, bradycardia, heart failure and after myocardial infarction (azithromycin and ciprofloxacin SmPCs).

Avoid the combination: the ciprofloxacin label of the US Food and Drug Administration (FDA) says to avoid ciprofloxacin in patients taking macrolides and other drugs that prolong the QT interval (ciprofloxacin FDA label). The Spanish SmPCs of both antibiotics allow the combination only with caution (azithromycin and ciprofloxacin SmPCs). If the combination cannot be avoided, note that the FDA label also says to avoid ciprofloxacin with known QT prolongation, uncorrected hypokalaemia or hypomagnesaemia, heart failure, myocardial infarction or bradycardia (ciprofloxacin FDA label). Older patients and women are more sensitive to QT prolongation (azithromycin and ciprofloxacin SmPCs).