A peptic ulcer is a sore in the lining of your stomach or upper small intestine. Ulcers form when the protective layer in the lining has broken down, often because of an infection with Helicobacter pylori (H. pylori) bacteria or use of nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs include aspirin, ibuprofen (Advil or Motrin), and naproxen (Aleve).

Peptic ulcers can cause pain in the belly, above the belly button. Ulcers can also bleed.