A peptic ulcer is a sore in the lining of the stomach or duodenum caused by bacteria called Helicobacter pylori or non-steroidal anti-inflammatory drugs like aspirin. Symptoms include a burning pain in the gut that occurs a few hours after eating and keeps people awake at night. Treatment involves antibiotics to kill H. pylori bacteria and proton pump inhibitors or histamine blockers to reduce stomach acid. Following treatment, lifestyle changes like quitting smoking and limiting NSAID use can help prevent ulcers from returning.