How long it takes for a lactose intolerant baby to get well is mainly related to the specific type and individual factors of the patient, and should be analyzed on a case-by-case basis, and cannot be generalized. Lactose intolerance is a common phenomenon in Asian groups, mainly due to the weak gastrointestinal tract of young children and the imperfect development of the villi of the small intestinal wall, so the amount of lactase secreted in the body is low and not enough to break down the lactose in breast milk or milk powder. The child will have diarrhea with thin yellow stools, sometimes with foam, crying, milk aversion and stunting. In case of congenital lactose intolerance, there is no cure, only relief by using lactose-free formula or lactase supplementation. In the case of secondary factors, such as rotavirus infection causing temporary lactose intolerance, symptoms can return to normal within 5-7 days. Children who develop lactose intolerance need to be seen by a pediatric gastroenterologist in a timely manner, and appropriate treatment measures should be taken under the guidance of the doctor.