Summer diarrhea in four-month-old babies may be caused by the poor dietary structure of the breastfeeding mother recently, and may also be caused by infectious enteritis, which can be treated by general treatment and oral medication. 1. Poor dietary structure of breastfeeding mothers: If breastfeeding mothers eat too much spicy, greasy, stimulating food in the summer, then it may affect the milk secretion of breastfeeding mothers, which may lead to four-month-old babies have diarrhea in the summer, in this case, breastfeeding mothers need to improve the structure of the diet, to easy to digest and nutritious meats, vegetables and fruits, and eat less spicy, stimulating food. 2. Infectious enteritis: four-month-old babies can be caused by bacterial and viral infections, infectious enteritis, diarrhea symptoms, such as bacterial infections, according to the drug sensitivity to give antibacterial drugs such as cefixime, such as viral infections, self-limiting, can not be special treatment. At the same time, oral bifidobacteria and other probiotics to regulate, diarrhea can be severe oral montelukast to stop diarrhea. It is recommended that four-month-old babies with diarrhea in summer should consult a doctor in time to find out the cause of the diarrhea and treat it positively. The above medications should be used in accordance with medical advice.