In normal digestion, food travels from the mouth through the esophagus into the stomach, where it is broken down by gastric juice containing hydrochloric acid, mucus, and enzymes like pepsin. From there, food passes into the duodenum, where absorption begins.
Gastric ulcers and duodenal ulcers occur when the protective mucous layer is damaged by stomach acid. Depending on the location, the condition is classified as either a gastric ulcer (in the stomach) or a duodenal ulcer (in the upper small intestine).
Each year, more than 4 million cases of ulcer disease are diagnosed globally. In the U.S. alone, over 20 million people are affected by stomach ulcers at some point in their lives. Duodenal ulcers are more common among men aged 30–50, while gastric ulcers occur more often in women over 60.