At times there will be inflammation of the duodenum rather than, or sometimes before, there is an ulcer. When there is inflammation of the tissue like this, it is called duodenitis. Images 1 and 2 show two instances of acute reddening and localized swelling of the duodenal cap. This type of inflammation can be caused by the bacteria infection, Helicobacter pylori and by arthritis and pain drugs such as aspirin, Advil, Motrin, Naprosyn and many others. Other more unusual conditions such as Crohn's disease can also cause inflammation.