Often a vague pain in the lower abdomen after meals may be caused by irritable bowel syndrome, ulcerative colitis and other diseases. 1. Irritable bowel syndrome: a common functional gastrointestinal disease, can be caused by visceral hypersensitivity, food allergy, food intolerance, abnormal gastrointestinal dynamics, neurological abnormalities, intestinal infections, mental and psychological disorders, etc., can appear after meals, lower abdominal pain, persistent or intermittent diarrhea, constipation, heartburn and other symptoms. 2. Ulcerative colitis: it is a chronic non-specific intestinal inflammatory disease, mainly involving the rectum and colon, and is a recurrent chronic course. It manifests itself in intermittent diarrhea, mucus, pus and blood stools, lower abdominal pain after meals, and symptoms such as urgency and heaviness (discomfort in the lower abdomen, wanting to defecate very much, and feeling of incomplete defecation after defecation), and it can also have extra-intestinal manifestations in the skin, mucous membranes, joints, eyes, liver and gallbladder, etc. It is often characterized by a vague feeling in the lower abdomen after meals. Often after meals, lower abdominal pain, in addition to irritable bowel syndrome and ulcerative colitis, do not exclude the possibility of digestive tract tumors, female patients may also be gynecological diseases, it is recommended to seek medical attention to clarify the diagnosis, under the guidance of the doctor for targeted treatment.