Babies who have diarrhea when they are breastfed may be due to lactose intolerance, improper mother’s diet and other reasons. 1. Lactose intolerance: the baby’s body lacks lactase, which can lead to lactose intolerance. Breast milk contains a large amount of lactose, the baby can not be broken down to absorb the phenomenon of breast milk diarrhea, usually without special treatment. 2. Mother’s diet: mother eat spicy, stimulating, cold, greasy food, food decomposition and absorption will be part of the milk to the baby, will lead to the baby eating breast milk diarrhea. Mothers can improve their diets to alleviate the symptoms of diarrhea in babies, focusing on light and mild foods. If your baby’s diarrhea on breastfeeding is more serious and cannot be relieved, it is recommended that you seek medical attention as soon as possible and follow the doctor’s instructions for treatment.