Incidence of Rash After Amoxicillin Treatment in Children With Infectious Mononucleosis

WHAT'S KNOWN ON THIS SUBJECT: Antibiotics-induced rash in Epstein-Barr virus acute infectious mononucleosis, especially the aminopenicillins-induced type, was first described during the 1960s, with a reported incidence of 80% to 100%. This phenomenon was not further investigated but is well-established in pediatric textbooks. WHAT THIS STUDY ADDS: The main observation of this study is that rash induced by amoxicillin in confirmed Epstein-Barr virus acute infectious mononucleosis was found at a rate of ∼30%, which is much lower than previously reported. abstract "Ampicillin rash," a phenomenon unique to patients with Epstein-Barr virus acute infectious mononucleosis (AIM) treated with ampicillin, was first reported in the 1960s. The incidence was estimated as being between 80% and 100%, and the figures have not been reviewed since those first accounts. We sought to establish the current incidence of rash associated with antibiotic treatment among children with AIM. RESULTS: Of the 238 children who met the study entry criteria during the study period, 173 were treated with antibiotics. Fifty-seven (32.9%) of the subjects treated with antibiotics had a rash during their illness compared with 15 (23.1%) in untreated patients (P = .156; not significant). Amoxicillin was associated with the highest incidence of antibiotic-induced rash occurrence (29.5%, 95% confidence interval: 18.52-42.57), but significantly lower than the 90% rate reported for ampicillin in past studies. Age, gender, ethnicity, and atopic or allergic history were not associated with the development of rash after antibiotic exposure. Among the laboratory data, only increased white blood cell counts were more prevalent among subjects who did not develop an antibiotic-induced rash. CONCLUSIONS: The incidence of rash in pediatric patients with AIM after treatment with the current oral aminopenicillin (amoxicillin) is much lower than originally reported. Pediatrics 2013;131:e1424- e1427