A peptic ulcer is a sore that forms in the gastrointestinal tract. Peptic ulcers occur when stomach acid and digestive juices break down and corrode the lining of the esophagus, stomach or duodenum, the upper portion of the small intestine. Peptic ulcers get their name from pepsin, one of the stomach enzymes that helps digest food. Although many people think that peptic ulcers occur only in the stomach, the majority of them occur in the duodenum.

The stomach and the surrounding portions of the GI tract provide a delicately balanced environment to process food. Strong acids and other chemicals in the stomach break down food into more basic components that can move through the digestive system. These chemicals, or gastric juices, are also strong enough to damage the lining that protects the stomach and other GI organs. A complex, multilayered coating forms a barrier to protect the lining.

This barrier is composed of many elements, including mucus, bicarbonate and chemicals called prostaglandins. Any change among the balance of these elements can weaken the barrier, allowing gastric juices to damage the underlying tissue. At first this damage may only irritate or inflame the lining, a condition called gastritis. Eventually enough corrosion forms a sore called a peptic ulcer.

Most peptic ulcers are the size of a pencil eraser or smaller. Peptic ulcers may heal on their own, only to recur after some time. Peptic ulcer disease refers to a tendency to develop these recurrent ulcers.

Peptic ulcers are quite common. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), one in every 10 Americans will develop a peptic ulcer at some time in their lives. Duodenal ulcers occur most frequently in patients between the ages of 30 and 50 years and are twice as common in men as in women, according to the American College of Gastroenterology (ACG). Gastric ulcers tend to occur after the age of 60 years and are more common in women.

Peptic ulcers are generally referred to by their locations and sometimes by how they were formed. Different types of peptic ulcers include:

• Duodenal ulcers. This most common type of peptic ulcer forms in the duodenum.
  
  
• Gastric ulcers. Occur in the stomach, usually along the upper curve of the stomach.
  
  
• Esophageal ulcers. Occur in the lower section of the esophagus, where they form when stomach acid backs up or refluxes into the esophagus.
  
  
• Stress ulcers. May develop in the stomach or duodenum following severe illness, injury or trauma, such as severe burns or peritonitis.
  
  
• Marginal ulcers. Also known as anastamotic ulcers, these may occur following the removal of part of the stomach (partial gastrectomy), where the remaining stomach connects to the small intestine.

Peptic ulcers sometimes produce no symptoms, and as a consequence, may go undetected while they worsen. Left untreated, ulcers continue to corrode the GI lining and may eventually lead to serious complications. Potential complications of peptic ulcers include:

• Hemorrhage (bleeding). Bleeding ulcers may not produce pain, but may include hematemesis (vomiting blood), melena (black, tarry stool), dizziness and fainting.
  
  
• Penetration. An ulcer cuts through the wall of the stomach or duodenum and continues into a nearby organ (e.g., liver, pancreas).
  
  
• Perforation. An ulcer cuts through the stomach or duodenum wall and creates a direct opening to the abdominal cavity (peritoneum), allowing the contents of the organ to spill out. This invasion of the peritoneum may lead to an infection or inflammation called peritonitis, which can be fatal if left untreated.
  
  
• Obstruction. Swelling or scarring around an ulcer narrows the opening from the stomach to the duodenum, preventing food from properly passing through. Patients often vomit large volumes of food eaten hours before.