What is a duodenal ulcer? A duodenal ulcer is a type of peptic ulcer that occurs in the duodenum, the beginning of the small intestine. Peptic ulcers are eroded areas in the lining of stomach and duodenum, which result in abdominal pain, possible bleeding, and other gastrointestinal symptoms. The most common cause of duodenal ulcer is a stomach infection associated with the Helicobacter pylori (H pylori) bacteria. Other risk factors for duodenal ulcers include overuse of alcohol, tobacco, and medications such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs). Severe illness has also been implicated as a risk factor in the development of duodenal ulcer. The signs and symptoms of duodenal ulcer can be constant or sporadic, and the disease course varies among individuals. If H pylori is the cause of the ulcer, the symptoms will remain as long as the infection is untreated. Some people with duodenal ulcers have no symptoms at all, while others may have burning pain, severe nausea, and vomiting. In the case of H pylori-related duodenal ulcer, the infection can be treated successfully with antibiotics. For a duodenal ulcer not related to H pylori, antacids or other medications are an effective treatment. You can reduce your risk of H pylori infection by following commonsense hygiene practices such as washing your hands with soap and water prior to preparing food and after handling dirty diapers or using the bathroom. Seek immediate medical care (call 911) if you, or someone you are with, have serious symptoms such as severe abdominal pain, bloody or black tarry stools, or bloody or black vomit. Seek prompt medical care if you are being treated for duodenal ulcer and mild symptoms recur or are persistent.