A nonmalignant ulcer that develops in the portion of the gastrointestinal tract that is exposed to gastric secretions. Peptic ulcers occur in the stomach or duodenum. Common symptoms include epigastric abdominal pain and anorexia. Complications include perforation, penetration (into adjacent organs), and bleeding. The microorganism Helicobacter pylori has been implicated in the development of peptic ulcer disease. For this reason, new therapies may now involve the use of oral antibiotics. More common in blood group O.