Diarrhea is one of the most commonly encountered clinical symptoms, especially in the hot season or after eating unclean and cold food. Therefore, most people are under the impression that diarrhea means enteritis or food poisoning. Antibiotics are always used for diarrhea patients, and they have cured many of them, but they are not known to be harmful to some patients with non-infectious diarrhea. Here, it is necessary to call for a new understanding of diarrhea. Diarrhea refers to an increase in stool water and stool frequency, i.e. stool frequency more than 3 times per day, stool volume more than 200 grams per day, and water more than 85% of the total stool volume, often accompanied by a sense of stool urgency and abdominal and perianal discomfort. The pathogenesis of diarrhea is as follows: 1. osmotic diarrhea: eating a large amount of unabsorbable solutes, so that the osmotic pressure in the intestinal cavity rises, and a large amount of liquid passively enters the intestinal cavity and causes diarrhea. It is characterized by: (1) stool volume less than 1 liter per day; (2) cessation or significant reduction; (3) increased acidity of stool, PH around 5 (normal is close to 7). Most commonly seen in congenital lactase deficiency, pancreatic exocrine insufficiency, small intestinal mucosal lesions caused by malabsorption, short bowel syndrome, intestinal bacterial overgrowth, taking hypertonic laxatives such as magnesium sulfate, mannitol, lactulose, etc.; 2, secretory diarrhea: diarrhea caused by excessive secretion of water and electrolytes from the gastrointestinal tract or by inhibition of absorption. Characterized by: (1) stool volume more than 1 liter per day; (2) stool is watery, without pus and blood; (3) stool PH or alkaline or neutral; (4) its fasting 48 hours after the diarrhea still persists. The pro-secretory substances that cause secretory diarrhea include bacterial enterotoxins (the most typical example is cholera), endogenous pro-secretory substances (the most typical examples are vasoactive intestinal peptide tumors and gastrinomas), endogenous or exogenous laxative substances such as bile acids, fatty acids, and certain laxatives; 3. Exudative diarrhea: diarrhea caused by the integrity of the intestinal mucosa that is not damaged by inflammation or ulceration, resulting in massive exudation The diarrhea is characterized clinically by pus and blood stools, which can often be accompanied by symptoms of inflammation or infection of the abdomen or the periphery. Exudative diarrhea is divided into two categories: infectious and non-infectious, and infection is the most common cause of exudative diarrhea, including bacterial, viral, parasitic and fungal infections. The causes of non-infectious exudative diarrhea include inflammatory bowel disease, intestinal tumors, radiation enteritis, etc.; 4. abnormal gastrointestinal motility diarrhea: due to excessive gastrointestinal motility, resulting in shortened contact time between water and electrolytes and intestinal epithelial cells in the gastrointestinal tract, directly affecting the absorption of water causing diarrhea. It is mainly seen in irritable bowel syndrome, malignant carcinoid syndrome, hyperthyroidism, major gastrectomy and diabetes mellitus.