Diarrhea in a 3-month-old baby may be related to cold in the abdomen, improper feeding, formula allergy, or may be caused by pathogenic infection. Parents should promptly take their babies to the hospital for stool tests to determine the cause and treat the symptoms. Common causes and symptoms: 1, abdominal cold: baby because of abdominal cold, resulting in accelerated intestinal peristalsis, it is easy to appear diarrhea symptoms, mainly manifested as watery or green stool; 2, improper feeding: parents to baby drinking too much milk powder, or in hot weather to baby weaning, easy to cause the baby diarrhea, the main symptoms are frothy stool, and emit sour smell; 3. Milk powder allergy: formula-fed babies who have diarrhea for a long time need to pay attention to the situation of milk protein allergy, if necessary, replace the deeply hydrolyzed formula; 4, pathogens infection: babies eat unclean food, resulting in bacterial or viral infections, causing intestinal inflammation, which can cause diarrhea phenomenon. Symptoms are mainly manifested as thin stools, accompanied by vomiting, fever and other symptoms. Treatment 1, 3 months old baby diarrhea, if the spirit, appetite are relatively good, no dehydration symptoms, parents can feed the child probiotics under the guidance of the doctor to regulate intestinal flora; 2, if the baby’s stool water is a lot, can be fed under the guidance of the doctor to take montelukast to relieve diarrhea symptoms; 3, consider allergies timely replacement of milk powder formula; 4, if the infection factors caused by the cause of treatment. Note 1, to breastfeed the baby mother should pay attention to appropriate light diet, drink more water, do not eat spicy and stimulating, greasy, too cold food to avoid fire; 2, the baby during diarrhea, the intake of nutrients can not be well absorbed, in order to ensure nutritional intake, parents should pay attention to the baby to increase feeding.