The sour smell of the stool of an exclusively breastfed baby may belong to the normal physiological situation, but it may also be related to lactose intolerance, indigestion, enteritis and other factors. If your baby has other discomforts, you should promptly go to the hospital for examination to clarify the causes.1. Normal physiology: most of the stools of exclusively breastfed babies have a slight sour smell, mainly because the gastrointestinal tract of infants and young children does not function well, coupled with the short intestinal tract of small infants, peristalsis is faster and cannot be effectively absorbed. The lactose content in breast milk is high, and the lactose that is not fully absorbed will be partially decomposed by the intestinal bacteria, forming acidic substances, thus producing a slight sour odor. The slight sour smell of the stool of an exclusively breastfed baby is normal and can be relieved when the baby grows up; 2, lactose intolerance: such babies will have sour stools after eating milk powder or milk containing lactose, so pay attention to whether the child has other manifestations. Such as every time you drink milk powder will have diluted stools, you need to give your baby special formula, try to avoid eating food containing lactose, milk protein; 3, indigestion: breastfeeding too fast, too much, coupled with the incomplete development of the gastrointestinal tract function of infants and young children, can cause indigestion in babies, sour stools. In mild cases, appropriate hot compresses or massage the baby’s abdomen to promote intestinal peristalsis. If it cannot be relieved, you can seek medical attention and follow the doctor’s instructions to be given pediatric elimination granules, probiotics and other drugs; 4, enteritis: if the placed breast milk deterioration, internal bacterial growth, baby eating can lead to enteritis, sour stools, with abdominal pain, diarrhea and other symptoms, should be given montelukast, ceftriaxone and other medication. If your baby’s stool is sour, parents can give your baby more warm water and pay attention to keeping your baby warm to avoid catching a cold. In addition, the mother herself also needs to eat a light diet, eat more fresh vegetables and fruits to ensure a balanced nutrition. Pay attention to more rest, keep a happy mood, and ensure the quality of breast milk.