Lactose intolerance is caused by the decrease of lactase secretion in the baby’s body, which cannot fully absorb and digest the lactose in breast milk or milk powder, and the main symptom is diarrhea. If the baby still has obvious diarrhea after the mother avoids eating, it is recommended to add lactase to breastfeeding; if it is mixed feeding or artificial feeding, feed the baby with lactose-free formula and temporarily reduce the number of breastfeeding. After a week or so, you can slowly reduce the number of lactose-free formula feedings from less to more, and breast milk gradually increases, so that the child has an adaptation process that can improve the symptoms of lactose intolerance.