Most babies with allergies and blood in the stool do not get better on their own. Milk protein allergy is common when babies are allergic. When the intestinal barrier is damaged by milk protein allergy, rectal bleeding with bright red blood is serious. If allergic factors are not removed, most of the blood in the baby’s stool due to allergy will not heal on its own, and medical attention is needed at this time. If the diagnosis of milk protein allergy is clear, the feeding plan should be adjusted according to the clinical symptoms and laboratory tests, after the doctor’s comprehensive judgment, such as switching to deeply hydrolyzed protein formula or amino acid formula powder, and gradually switching to transition after 3-6 months of feeding. This is because by cutting the intact milk protein into short peptides or amino acids, thus reducing the allergenicity of milk protein, only by changing the root cause will the rectal bleeding caused by allergy in babies be relieved.