Breast milk is the best food for infants and young children, so it is generally recommended to exclusively breastfeed for 6 months, and then add complementary foods after 6 months, some exclusively breastfed babies will have diarrhea, called “breast milk diarrhea”. Breastfeeding diarrhea is mostly seen in small infants within 6 months of age, generally soon after birth, diarrhea, stools are mostly foamy and dilute watery, sometimes containing milk flaps, occasionally green, with strips of transparent mucus, the smell has a special sour smell. The stools are generally frequent, ranging from 3 to 20 times a day. Children with breastfeeding diarrhea are generally in good spirits, eat enough milk, and have normal weight gain, typically characterized by “eating, pooping, and growing at the same time”, without abnormalities such as weight gain, choking, milk spillage, vomiting, bloating, abdominal pain, and crying after eating milk. Therefore, if a breastfed baby has slightly diluted stools and does not show any disease, it usually does not need special treatment and will get better after adding complementary foods. Breastfeeding mothers should also pay attention to their diet in daily life. If the mother often eats foods with a lot of oil, high fat and irritants, resulting in the milk containing more ingredients than the baby needs, it may cause diarrhea in the baby. In addition, the mother should avoid eating foods that can cause allergies in the baby. For example, if the baby is allergic to milk, eggs, seafood, wheat, etc., the mother may also experience increased diarrhea or even blood in the stool if the baby eats these foods. If the mother’s diet is still not enough to improve the baby’s diarrhea, she can give her baby some lactase to help digest the lactose in breast milk. However, if the baby has sudden onset of diarrhea within a short period of time, with a significant increase in the number of stools or mucus-purulent stools, along with a significant decrease in appetite, frequent vomiting, decreased urine output, frequent crying, fever, poor weight gain, and eczema, it is important to consider other causes of diarrhea and seek medical treatment promptly.