Published: 10 June 2015


Macrolides - Don't Upset the Rhythm

Prescriber Update 36(2): 22
June 2015

Key Messages

  • Macrolide antibiotics (azithromycin, clarithromycin, erythromycin and roxithromycin) are associated with a small increased risk of abnormal heart rhythms such as QT interval prolongation, which may rarely result in sudden cardiac death.
  • The risk is increased in patients with other cardiovascular risk factors and in patients taking other QT prolonging medicines.


Medsafe and the Medicines Adverse Reactions Committee (MARC) have recently completed a review of the risk of cardiac arrhythmias and sudden cardiac death associated with the use of macrolide antibiotics.

In New Zealand, azithromycin, clarithromycin, erythromycin and roxithromycin are macrolide antibiotics approved for use. The MARC concluded that the macrolide class of antibiotics are associated with a small increased risk of abnormal electrical changes in the heart such as QT interval prolongation. These changes may rarely lead to sudden cardiac death.

Healthcare professionals should consider the risk of QT prolongation when weighing the risks and benefits of macrolide antibiotics, particularly in at-risk groups. At-risk groups include:

  • patients predisposed to QT interval prolongation such as those with a history of Torsades de Pointes or congenital long QT syndrome
  • patients taking other medications known to prolong the QT interval such as antiarrhythmics of classes IA and III (eg, amiodarone), antipsychotic agents (eg, risperidone, haloperidol), antidepressants (eg, citalopram), and fluoroquinolones (eg, ciprofloxacin)
  • patients with electrolyte disturbance, particularly in cases of hypokalaemia and hypomagnesaemia
  • patients with clinically relevant bradycardia, cardiac arrhythmia or cardiac insufficiency.

The Centre for Adverse Reactions Monitoring (CARM) has received 28 case reports of heart rate and rhythm disorders associated with the use of macrolides. Four of these cases were reported with clarithromycin, 10 with erythromycin, four with erythromycin ethylsuccinate and 10 with roxithromycin.

The reactions most commonly reported include palpitations, tachycardia and QT interval prolongation. In the majority of cases reported to CARM, adverse heart reactions occurred within 24 hours of initiating the macrolide antibiotic.

Medsafe is working with the relevant sponsors to ensure all macrolide antibiotic data sheets contain consistent information about these risks.

Further information about drug-induced QT interval prolongation, arrhythmias and Torsades de Pointes is available at:

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