Which adverse effect is associated with macrolide antibiotics and warrants monitoring?

• A. QT prolongation
• B. Nephrotoxicity
• C. Ototoxicity
• D. Hepatotoxicity

Answer: (A)

Macrolide antibiotics can affect the heart’s electrical activity by prolonging the QT interval, which can predispose to a dangerous arrhythmia called torsades de pointes. This risk is especially important in people with low potassium or magnesium, preexisting long QT syndrome, bradycardia, or when these drugs are used with other medications that also lengthen the QT. Because of that, monitoring is warranted—baseline and follow-up EKGs in high‑risk patients, plus checking electrolytes and reviewing drug interactions that could further prolong QT. While macrolides can rarely cause hepatotoxicity and are not typically associated with nephrotoxicity or ototoxicity in the same way as other antibiotics, the potential for QT prolongation has the clearest immediate clinical consequences and is the aspect that needs careful monitoring in practice.