Food enters the body through the mouth, then travels down the esophagus, and into the stomach. The stomach produces acid and an enzyme called pepsin, which aids in digestion. The stomach lining is protected from the digestive acids by a thin layer of mucus. Sometimes, an imbalance between the protective mucus and digestive fluids (stomach acids and pepsin) can develop. When this happens, an ulcer can form.
An ulcer is a sore that damages the lining of the stomach. Symptoms of a gastric ulcer can include abdominal pain that occurs after a meal, nausea, vomiting, weight loss, and fatigue.
Some gastric ulcers can be caused by infection with a bacterium called Helicobacter pylori. This bacteria exists in the stomach and can change the mucous layer that protects the lining from digestive acids. Cigarette smoking, foods and beverages containing caffeine, alcohol use, and certain medications may contribute to the development of gastric ulcers.