BACKGROUND: There are expanding indications for oral food challenges (OFCs). Although several studies have examined the risk of OFCs, little has been reported on allergic reactions during OFCs depending on the indication. This study assessed the prevalence, severity, and treatment of allergic reactions depending on the indication for OFCs. METHODS: We performed a prospective multicenter study between March 2012 and May 2013. Severity of symptoms elicited by OFCs was classified according to grading of anaphylaxis that ranges from grade 1 (most mild) to grade 5 (most severe). RESULTS: A total of 5062 cases (median age, 3.8 years; males, 65.2%) were analyzed. Allergic reactions were elicited in 2258 (44.6%) OFCs, of which 991 (43.9%) were classified as grade 1, 736 (32.6%) were classified as grade 2, 340 (15.1%) were classified as grade 3, and 191 (8.5%) were classified as grade 4-5. Epinephrine was administered in 7.1% (n = 160) of positive OFCs. Among the top three most common food allergens (hen's egg, cow's milk, and wheat), severity differed significantly depending on the indication for OFC, and adjusted standardized residuals indicated that severity of allergic reactions was higher for the indication to assess threshold level for oral immunotherapy. In addition, the prevalence of epinephrine use was highest for the indication to determine safe intake quantity. CONCLUSIONS: Our study suggested that prevalence, severity, and treatment of allergic reactions differ depending on the indication for OFC. Further studies are needed to determine differences in risks depending on the indication for OFC.