There are many causes of vague pain in the upper left side of the stomach, and the common causes are mainly the following: a. Stomach and spleen problems, usually caused by food or external stimuli, or inflammatory infections leading to pain. It may also be due to indigestion, causing excess gas in the stomach that cannot be discharged, resulting in distension and pain in the upper left side of the stomach. Second, acute enteritis, acute gastric mucosal damage, acute pancreatitis, and acute peritonitis are usually caused by excessive alcohol consumption, or overeating or binge eating. Third, inguinal hernia, left femoral hernia, hiatal hernia, etc., which are more common diseases in general surgery, also present symptoms of vague pain in the upper left side of the abdomen. Urological diseases, if men have vague pain in the upper left side of the abdomen, consider acute prostatitis, ureteral calculi, acute kidney stones, etc. V. Gynecological diseases, if women have vague pain in the upper left side of the abdomen, consider that it is caused by tubal inflammation, ovarian cyst, ovarian cyst torsion, ectopic pregnancy, ectopic pregnancy, ureteritis and other diseases.