Breast milk can cause diarrhea in 8-month-old babies, but there are other factors that can cause diarrhea in babies, such as climatic factors and intestinal infections. 1. Breastfeeding causes: improper breastfeeding can cause diarrhea, if the mother consumes spicy cold, too greasy, indigestible food may lead to diarrhea; some of the breast milk protein allergy of infants may be allergic to breast milk proteins, which leads to diarrhea; breast milk lactose can also lead to diarrhea of some of the infants intolerant to lactose. 2. Climatic factors: sudden changes in climate, abdominal cold, will increase intestinal peristalsis; when the weather is too hot, so that the secretion of digestive juices to reduce or thirst drink too much milk, can cause diarrhea in infants. 3. Infectious factors: intestinal infections can be caused by viruses, bacteria, fungi, parasites, bacterial and viral infections are common, especially viruses. Therefore, diarrhea in 8-month-old infants may be caused by breast milk or other factors. If an infant’s diarrhea is recurring or worsening, it is recommended to seek prompt medical attention to identify the cause and administer the correct treatment.