Common clinical manifestations of milk protein allergy in infants and children are as follows: 1. Gastrointestinal tract: dysphagia, frequent reflux, vomiting ± vomiting blood, intestinal colic, abdominal pain, anorexia, refusal to eat, diarrhea ± protein loss or blood in stool, constipation ± perianal rash. Growth retardation, stool OB (+), iron deficiency anemia. 2, Skin: urticaria (non-infectious, drug, etc.), atopic eczema, angioedema (lips, eyelids) 3, Respiratory: runny, wheezing, non-infectious chronic cough 4, Systemic manifestations: allergic reactions, shock, severe metabolic acidosis, vomiting, diarrhea (food-induced small bowel colitis syndrome, FPIES) Disease typing: mild-moderate (~90%), severe (~10%) 1 , mild-moderate: reflux, vomiting, diarrhea, constipation, colic/abdominal pain, atopic dermatitis, angioedema, urticaria, swollen mouth and lips, rhinitis, runny nose, wheezing, non-infectious cough, irritability, etc. 2. Severe: growth retardation, iron deficiency anemia, severe enteropathy (e.g. severe colitis, eosinophilic gastrointestinal disease and hypoproteinemia due to enteropathy), severe exudative/allergic dermatitis, laryngeal edema, acute allergy syndrome, shock, severe metabolic acidosis, vomiting, diarrhea (food-induced small bowel colitis syndrome, FPIES).