How old is the baby milk protein allergy can drink normal milk powder there is no fixed answer, usually 3-6 months of time, the baby milk protein allergy drink back to normal milk powder need to have a certain transition period. When the baby appeared milk protein allergy, you can replace the depth of hydrolyzed protein or partially hydrolyzed protein, amino acid milk powder, take 3-6 months, observe the baby whether the milk protein allergy related symptoms, if there is no allergic symptoms, you can slowly let the baby drink back to normal milk powder. The baby due to milk protein allergy drink the depth of hydrolyzed protein and other types of milk powder, need to be replaced by normal milk powder, there needs to be a slow transition stage, the depth of hydrolyzed protein and normal milk powder mix for a period of time, until completely replaced by normal milk powder, during the period of observation of the baby’s physical symptoms. Parents can also take their babies with milk protein allergy to the hospital for advice on formula feeding from the doctor.