Background/Objectives: Food Protein-Induced Enterocolitis Syndrome (FPIES) is a rare and poorly understood condition that primarily affects infants and young children. This study aimed to evaluate the clinical characteristics and outcomes of oral food challenge (OFC) tests in patients diagnosed with FPIES. Methods: A retrospective cohort study was conducted on pediatric patients who underwent OFCs for FPIES at a tertiary health service from January 16, 2018, to June 20, 2024. Both accidental and scheduled in-hospital OFC results were considered. Results: Five patients were included, and 19 OFCs were evaluated. Four patients underwent 4 OFCs each, and one patient underwent 3 OFCs. The mean age of the first symptom onset was 35 days (ranging from 3 days to 2 months). Before the first OFC, the mean duration of the elimination diet was 7 months, and for patients who required additional OFCs, was 11.6 months. Four patients were admitted to the intensive care unit. Two patients were being fed on formula, and three were having mixed feeding. Two patients had a personal and family history of atopy, and one had only a family history of atopy. Two patients had genetic syndromes. All patients developed tolerance to cow’s milk protein within a mean time of 44 months, ranging from 17 to 103 months. The two patients with genetic syndromes had a longer time to develop tolerance. Conclusions: FPIES may require multiple OFCs for diagnosis and management. The time to develop tolerance was longer in patients with genetic syndromes.
