There are many reasons that lead to vague pain in the left upper abdomen and want to vomit, and the common ones are gastrointestinal diseases, heart diseases, neurological diseases, fever caused by various reasons and other reasons. 1. Gastrointestinal diseases: various types of gastritis, gastric ulcer, duodenal ulcer, cholecystitis, pancreatitis, as well as tumors of the digestive tract, such as gastric cancer, esophageal cancer and so on. 2. Heart diseases: insufficient blood supply to the heart muscle, arrhythmia, myocarditis may also lead to vague pain in the left upper abdomen and want to vomit. 3. Neurological diseases: for example, gastrointestinal neurosis or psychosomatic diseases may also lead to vague pain in the upper left abdomen and want to vomit. 4. Fever: Fever caused by various reasons may cause congestion and swelling of the mucous membrane of the gastrointestinal tract, which may also lead to a vague pain in the upper left abdomen and want to vomit. There may be other reasons for the pain in the upper left abdomen, it is recommended to go to the hospital for examination, to clarify the cause of the disease and follow the doctor’s instructions for treatment.