Diagnosis and Management of Food Protein-Induced Allergic Proctocolitis

Food protein-induced allergic proctocolitis (FPIAP) is a frequent cause of rectal bleeding in otherwise healthy infants. Although benign and self-limited, wide variation in diagnostic and management practices often leads to overdiagnosis, unnecessary dietary restriction, and disruption of breastfeeding. This review summarizes contemporary evidence to guide a pragmatic, challenge-anchored approach to diagnosis and management.

Diagnosis of FPIAP remains clinical, based on symptom resolution after elimination and recurrence upon reintroduction of the trigger food; however, confirmatory challenges are seldom performed. Fecal calprotectin and other proposed biomarkers-such as eosinophil-derived neurotoxin, zonulin, and microbiome signatures-show poor reliability in infants and are not ready for clinical use. Management should prioritize the least restrictive diet - maternal dairy elimination for breastfed infants and extensively hydrolyzed formulas for formula-fed infants - only in challenge-proven FPIAP. Growing data support earlier reintroduction once colitis resolves, and early introduction of other allergens may reduce future IgE-mediated allergy risk. A standardized, challenge-confirmed framework minimizes over-restriction and supports continued breastfeeding. Future priorities include validation of non-invasive biomarkers and trials comparing timing and strategies for safe dietary reintroduction in FPIAP.