Five to six percent of children are allergic to milk proteins, and one to two percent are allergic to breast milk, which we call protein allergy or milk protein allergy. The most likely symptom of allergy is itchiness. If a child has eczema on his face, scratch his face, scratch his brain and scratch his body, itching is the first symptom. If it is more serious, the mucous membrane of the nasal cavity becomes infected, the child will have a blocked nose, sneeze and rub his nose. If the condition develops further, at five or six months of age, eczema of the external ear canal will appear, which means that the child will scratch and scratch his ears, or some children will poke their ears with their fingers, which is a sign of itchiness. In fact, another symptom is seborrheic dermatitis, where the child’s head itches and rubs his head all the time, especially when the child rubs his head on the adult and scratches it, and also when the child has oil on his head and sweats a lot, the child will lose hair and develop occipital baldness. In the past, we thought that occipital baldness was a sign of calcium deficiency, but in fact, occipital baldness is a typical symptom of allergies. These symptoms are reflected in the word “itchy”, which means that the child may be allergic. This is the best and easiest way to determine milk allergy because before 6 months of age, the child rarely eats supplementary foods, mainly milk.