“Pediatric food allergy” belongs to the category of food intolerance. Food intolerance in a broad sense refers to non-physiological reactions to food and food poisoning; food intolerance in a narrow sense refers to non-physiological reactions to food (because food poisoning is given a separate diagnosis in clinical practice). Food intolerance mechanisms include immune-mediated and non-immune-mediated reactions, while food allergy refers to immune-mediated causes, but also includes non-immune-mediated mechanisms when discussing the clinical manifestations of food and substance allergy. “Pediatric food allergy” also has obvious age-specific and allergen-specific features. In other words, there are differences in the mechanisms of occurrence, clinical manifestations, diagnostic methods, management and prognosis. Take milk protein allergy as an example. It is important to distinguish between small infants (meaning newborns ~3 months), infants (<1< span=""> years), and toddlers (1 to 3 years) preschool-age (~6 years) children. Among them, infants are common. A small number of hospitalized children present with severe systemic allergic reactions that require diagnosis and management such as special excitation tests. For outpatient cases, the treatment of feeding methods should be individualized according to whether or not complementary foods have been started and the different conditions of complementary food tolerance, which is a process of continuous observation, learning and adjustment. In conclusion, milk protein allergy manifests itself differently at each month and age, and the prognosis varies greatly. However, according to current clinical experience, the incidence of milk protein allergy in most small infants decreases significantly by 1 to 3 years of age (some literature suggests 6 years of age) (the role in the pathogenesis of respiratory allergy is discussed separately), so it is said to be a “growth and developmental problem”. This is why it is said to be a “growth and developmental problem”.