An Underrecognized Adverse Effect of Azithromycin: Agranulocytosis in a 67-Year-Old Man

The document reported a rare case of azithromycin-induced agranulocytosis in a 67-year-old man, characterized by an absolute neutrophil count (ANC) of 0 cells/μL following a 5-day course of the antibiotic. Initially presenting with chest congestion and bronchitis, the patient experienced a significant drop in white blood cells nine days after treatment, leading to hospitalization. Despite the rarity of drug-induced agranulocytosis, with an annual incidence of 3 to 16 cases per million, this case highlighted the potential for azithromycin to cause severe neutropenia. The patient's condition improved with ciprofloxacin prophylaxis, and his blood counts normalized within 12 days. This case was noted as the second reported instance of azithromycin-induced agranulocytosis in the literature.