Immediate and non-immediate allergic reactions to amoxicillin present a diagnostic dilemma: a case series

BACKGROUND: Allergic reactions to amoxicillin are very common occurrences in the pediatric age group; however, onset of symptoms can present a diagnostic dilemma. CASE PRESENTATION: We present a case series that describes three children (8-year-old white girl, 2-year-old white boy and 14-month-old Chinese boy) who presented with varied onset of allergic reactions to amoxicillin, specifically immediate (within the first hour after exposure) and non-immediate onset. One child developed immediate onset allergy to oral challenge with amoxicillin although his clinical history was evident for non-immediate onset allergy to amoxicillin. He was the only case that had a positive skin test to penicillin. Two other children presented with reactions toward the end of their treatment course of amoxicillin, yet one patient developed immediate onset allergy while the other patient developed non-immediate onset allergy after challenge. CONCLUSIONS: This case series demonstrates diagnostic challenges facing physicians assessing allergic reactions to amoxicillin. As onset of reactions can dictate severity and pathogenic type of allergy, a thorough clinical history and subsequent appropriate diagnostic testing including medication challenge can help establish the diagnosis.