Pain under the left side of the rib cage may be caused by some stomach diseases, such as patients suffering from chronic gastritis and gastric ulcer may have symptoms of pain in the left upper abdomen. Patients suffering from gastritis and gastric ulcer may have symptoms such as acid reflux, heartburn and abdominal distension in addition to pain in the left upper abdomen. If this happens, it is recommended to go to the hospital for a barium meal or gastroscopy, and if it is clear that you have gastritis or gastric ulcer, you can take some oral medication to suppress stomach acid for treatment. In addition, if there is H. pylori infection, antibiotic anti-H. pylori treatment is also needed. In addition, attention should be paid to regular eating habits, avoid spicy and stimulating foods, avoid stimulating beverages such as strong tea and coffee, avoid drinking alcohol, and eat more fresh and easily digestible foods.