Breast milk is the best food for infants, but for various reasons, breastfeeding is not possible and can be artificially fed, i.e. infant formula feeding, but some babies develop formula allergies. Certain proteins in milk such as α-s1 casein and β-lactoglobulin are currently recognized as allergens. Under normal circumstances, if the body can digest and absorb these two proteins, neither will cause an allergic reaction. However, for babies just a few months old, these proteins can induce allergic reactions. There are three main symptoms of a baby’s allergy to formula. The first is digestive symptoms, where the baby has repeated vomiting, diarrhea, bloating, constipation, and blood in the stool. The second is skin symptoms, the baby will appear eczema, acute hives. The third is the respiratory symptoms, the child has frequent unexplained coughing and sneezing, and severe asthma. Because of milk powder allergy babies are irritable, often cry, sleep disturbance, affect development, anemia and so on. Vomiting after eating milk may also lead to aspiration pneumonia, which may require injections and medication. If you find that your baby has the above three symptoms after feeding milk powder, you can basically be sure that your baby is allergic to milk powder, so you should promptly change your baby’s milk powder to anti-allergic milk powder and switch to amino acid milk powder or deeply hydrolyzed milk powder depending on the severity of the allergy. Of course, each baby’s performance may not be the same, so you can ask a professional pediatrician to determine the treatment plan.