Stomach pain and diarrhea after eating are mostly seen in intestinal diseases, such as acute enteritis, chronic enteritis, irritable bowel syndrome, and intestinal occupational lesions. After eating, food enters the intestine through gastric digestion, resulting in stimulation, leading to stomach pain and diarrhea, which can be judged according to stool characteristics and accompanying symptoms: 1, acute enteritis: often within a few hours after eating suddenly appear stomach pain, diarrhea, stool is watery, dark yellow or light green, foul-smelling, sometimes visible undigested food, usually without mucus and pus blood; 2, chronic enteritis: long-term chronic or recurrent The common symptoms are stomach pain and diarrhea, and sometimes constipation and diarrhea can alternate. According to the severity of the disease, the frequency of diarrhea and stool characteristics may vary, severe cases may appear mucus stool or watery stool. Some patients may have nocturnal diarrhea and postprandial diarrhea; 3, irritable bowel syndrome: commonly occurring after meals or before defecation stomach pain, diarrhea manifested by an increase in the frequency of stool, but each defecation volume is small, generally about 3-5 times a day, a few severe episodes up to 10 times. Mostly mucus thin stool, but no pus and blood, not frequent watery diarrhea; 4, intestinal occupational lesions: for some patients with intestinal occupational lesions, after eating, with the digestion of food, into the intestine, will stimulate the occupational lesions, resulting in bleeding, spasm and other conditions, stomach pain, diarrhea. For example, in the early stage of colon cancer, there may be manifestations such as pus and blood stool and increased number of bowel movements during defecation after meals, and abdominal pain is mostly vague and often located in the right lower abdomen. Intestinal polyps can be manifested as diarrhea, and when the polyps are larger, there can be hidden pain in the abdomen or a feeling of urgency.