Oral vancomycin is mainly used to treat and prevent active Clostridium difficile infection. Because it is widely believed that there is a very low absorption rate via the gastrointestinal tract, reports of adverse reactions following oral vancomycin administration are rare. This case report describes for the first time a case of antibiotic-associated diarrhoea in a 2-month-old infant treated with oral vancomycin. After oral vancomycin treatment, the number of eosinophils increased significantly and the levels gradually recovered after drug withdrawal. A review and analysis of the previously reported adverse reactions caused by oral vancomycin and eosinophilia caused by vancomycin confirm the need for physicians to pay close attention to vancomycin-related adverse reactions, to monitor the required concentration and to measure eosinophil counts in patients with rash-related adverse reactions. Patients with concomitant diseases and children should be monitored for adverse events as it is possible that they have increased gastrointestinal absorption of vancomycin following oral administration. When vancomycin causes eosinophilia, fever and rash, physicians should be alert to the possibility of organ damage.
Keywords: Oral vancomycin; adverse reactions; eosinophils; infant.