What is duodenitis? Duodenitis is inflammation occurring in the duodenum, the beginning of the small intestine. Inflammation in the lining of the duodenum may result in abdominal pain, bleeding, and other gastrointestinal symptoms. The most common cause of duodenitis is a stomach infection associated with a type of bacteria called Helicobacter pylori (H pylori). This organism disrupts the mucus barrier that normally protects the delicate duodenal lining from acidic stomach contents. Loss of this barrier predisposes a person to chronic inflammation and duodenal ulcer. Many people become infected with H pylori at a young age, but symptoms most commonly do not appear until adulthood. In some people, H pylori infection causes duodenitis, which, if untreated, may lead to an ulcer (open sore) in the duodenum. Severe illness and prolonged use of medications such as nonsteroidal anti-inflammatory drugs (NSAIDs), alcohol, or tobacco may also lead to duodenitis. Less commonly, Crohn’s disease can cause duodenitis. The signs and symptoms of duodenitis can be constant or sporadic, and the disease course varies among individuals. If H pylori is the cause, your symptoms will remain as long as the infection is untreated. Some people with duodenitis have no symptoms at all, while others may have burning pain or nausea with or without vomiting. In the case of H pylori-related duodenitis, the infection can be treated successfully with antibiotics. For duodenitis not related to H pylori, medications that reduce stomach acid can be 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. Lifestyle changes, such as limiting alcohol consumption and limiting your use of nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce your risk of duodenitis that is not related to H pylori. Seek immediate medical care (call 911) for 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 duodenitis but mild symptoms recur or are persistent.