Lack of sufficient lactase is the real cause of lactose intolerance in babies, so in principle, the problem can be solved by supplementing with lactase. Lactose intolerance is not a disease, it is just the inability of the digestive system to digest lactose. You can prevent this condition and reduce this symptom by adding lactase appropriately and by paying attention to your diet, by eating lactase and lactose-free formula. The correct approach is to add lactase drops to the milk when the baby drinks it to compensate for the lack of lactase in the baby’s body and to help pre-break down the lactose that was previously unable to be digested and absorbed in the small intestine. This prevents the baby from developing lactose intolerance without losing the nutritional content of the milk. Children with lactose intolerance do not need special treatment if their stools are infrequent and do not affect their growth and development. If diarrhea is frequent and weight gain is slow, dietary modification is needed. Some children with diarrhea can develop transient lactose intolerance, and if the acute phase is accompanied by dehydration, intravenous or oral fluid supplementation should be used first to correct dehydration. Lactose-free formulas (including cow’s milk-based or soy-based lactose-free formulas) can be used first, and then the frequency of breastfeeding can be gradually increased to a mixture of breast milk and lactose-free formula after the diarrhea has stopped, depending on the child’s tolerance. The general principle of substitution is not to reduce the nutritional needs of the child, and the diarrhea will gradually stop when he/she can add complementary foods and reduce breast milk or cow’s milk, with a good prognosis.