The pain under the ribs on the left side of the stomach may be caused by chronic gastritis, gastric ulcer and other diseases, which can be treated by medication and surgery. 1. Chronic gastritis: chronic gastritis may be due to damage to the gastric mucosa, resulting in increased secretion of gastric acid, which stimulates the gastric mucosa, resulting in vague pain in the left upper side of the stomach under the ribs, can be treated with oral medication such as aluminum thioglycollate, omeprazole and other drugs. Chronic gastritis patients, if the drug treatment did not get relief, can be in gastroscopy submucosal dissection or mucosal resection. 2. Gastric ulcer: the stomach left side of the ribs under the hidden pain may also be caused by gastric ulcer, you can take oral omeprazole, bismuth potassium citrate, sodium bicarbonate and so on for treatment. If gastric ulcer patients do not get relief from medication, they can undergo surgery to remove a large portion of the stomach. The left upper side of the stomach under the ribs hidden pain may also be pancreatic cancer and other factors, it is recommended to go to the hospital in a timely manner, clear the cause of the disease according to the doctor’s guidance for standardized treatment. Usually pay more attention to rest, do not exertion.