A peptic ulcer is a sore on the lining of the stomach or duodenum, which is the beginning of the small intestine. Peptic ulcers are common, as 10 percent of Americans develop them at some time in life. The cause of many peptic ulcers is a bacterial infection, but some ulcers are caused by long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), like aspirin and ibuprofen.
