Ulcers occur in the stomach or duodenum. Peptic ulcers are open sores that develop on the inside lining of your stomach and the upper portion of your small intestine (duodenum). The most common symptom is a dull or burning pain in the belly between your breastbone and your belly button. They can also cause bleeding, perforation or obstruction.
The two most common causes of peptic ulcers are infection with the bacterium Helicobacter pylori (H. pylori) and long-term use of aspirin and certain other painkillers, such as ibuprofen (Advil, Motrin, and others) and naproxen sodium (Aleve, Anaprox, and others).