The baby’s diarrhea after drinking milk may be related to breast milk diarrhea, or it may be caused by lactose intolerance, milk protein allergy and other reasons. 1. Breastfeeding diarrhea: It is mostly considered that breast milk may be due to the high content of lysozyme, prostaglandins, fat, etc., which is beyond the infant’s ability to digest and absorb, and thus may cause diarrhea after drinking milk. This is a physiological diarrhea and does not require special intervention. 2. Lactose intolerance: usually due to the lack of lactase enzyme in the baby’s body, the lactose in the breast milk or milk powder can not be effectively broken down, which may lead to diarrhea after drinking milk, and may be accompanied by abdominal distension, abdominal cramps and other manifestations. 3. Milk protein allergy: it is usually caused by the immune system of the baby’s body overreacting to the milk protein and forming an allergic reaction, which can lead to the baby’s diarrhea after drinking milk, and can be accompanied by abdominal pain, vomiting, diarrhea and other manifestations. The baby’s diarrhea after drinking milk may also be related to other factors, it is recommended to consult a doctor as soon as possible, after a clear diagnosis of the cause, to give targeted treatment and conditioning.