Under normal circumstances, breastfed newborns have 2 to 5 or even 8 to 10 stools per day, with thin stools, good mental status, good milk intake and normal weight gain. However, if the newborn has egg-flake soup-like stools, sour smell, mucus in the stool, mixed with blood, or accompanied by fever, do not like to eat milk, vomiting, abdominal distension, crying, etc., then you need to seek medical attention. Pathological diarrhea in newborns is divided into infectious diarrhea and non-infectious diarrhea. Infectious diarrhea can be caused by viral, bacterial, fungal and other infections of the intestinal tract. Non-infectious diarrhea is mostly caused by newborns’ allergy to milk protein, lactose intolerance, indigestion, and cold. Newborns have immature digestive function, low acidity of gastric juice, insufficient secretion or low activity of digestive enzymes, and low tolerance to food, and if they are not fed properly, newborns will develop diarrhea. If the formula is not brewed at the correct concentration, if the formula is changed, if sugar is added to the formula, if the milk is too cold or if starchy foods such as rice paste are added too early, this can easily lead to diarrhea in newborns. When diarrhea occurs in newborns, different treatments are administered depending on the cause and the severity of the diarrhea. Bacterial diarrhea requires antibiotic treatment and an adequate course of treatment to avoid recurrence; viral diarrhea or diarrhea from other causes should not be abused for antibiotics, which can affect recovery. For milk protein allergy or lactose intolerance, special formulas with hydrolyzed protein, amino acid powder or lactose-free formula need to be replaced. In addition, newborns with diarrhea can take sixteen-angle montmorillonite (Simethicone) to protect the gastric mucosa or probiotics to regulate the intestinal flora and promote recovery from the disease. In case of severe diarrhea, dehydration, acidosis, electrolyte disorders, etc., fluid infusion therapy is required.