BackgroundAspirin remains a key component of the standard therapy for Kawasaki disease (KD) in children. Although it is well known that aspirin can cause hypersensitivity such as aspirin-induced urticaria (AIU), AIU in children with KD has not been described.MethodsA retrospective case-control study was conducted to investigate AIU clinical features, biochemical parameters, treatment and outcomes in children with KD. Furthermore, biomarkers for predicting AIU were explored using the receiver operating characteristic (ROC) curve analysis.ResultsWe identified 46 AIU cases with 22 boys and 24 girls during April 2015–May 2019. Eighty-nine age-matched KD patients without AIU were randomly chosen as controls. The proportions of children with allergy history and aspirin doses administered in the 2 groups were found not to be significantly different. AIU group had substantially higher baseline C-reactive protein and NT-proBNP levels, and increased neutrophil percent. AIU appeared 6.0 (4.0, 8.0) days after aspirin treatment. Aspirin withdrawal and anti-allergic treatment were applied for AIU, and AIU disappeared in 1–3 days. Baseline NT-proBNP predicted AIU with an AUC of 0.70 (95% CI [0.60 to 0.79]) for sensitivity and specificity of 72.1% and 62.5%, respectively, for a cut-off value of 612.9 mg/L. The length of hospital stay for AIU patients was significantly greater compared with controls.ConclusionAIU in KD children is not related to gender or aspirin dose, and those with AIU have more severe inflammation at admission. Aspirin should be withdrawn for AIU management. Baseline NT-proBNP may serve as a valuable biomarker to predict AIU.