Moderate
Azithromycin × Fluconazole
Macrolides×Antifungals, triazole derivatives
Mechanism
Additive QT prolongation – both drugs prolong QTc dose-dependently.
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 courses of both (azithromycin 3–5 days, fluconazole single dose for candidiasis), the combination is acceptable. For prolonged systemic fluconazole therapy: alternative antibiotics (doxycycline, a cephalosporin) or antifungals (terbinafine, echinocandins).