The mechanisms of development of duodenitis have not yet been studied. Usually, the process of inflammation develops under the influence of irritating and damaging factors on the protective mechanisms of the gastroduodenal zone. In accordance with the nature of the symptoms of the disease, acute and inveterate forms of duodenitis are distinguished. Acute form - is rare and usually followed by inflammation in the stomach or bowel. The inveterate form is divided into primary and recurrent duodenitis. Primary duodenitis can develop as a result of a previous acute form of the disease. Recurrent inveterate duodenitis is one of the most common pathologies of the duodenum. This type of duodenitis develops as a complication against the background of certain chronic pathologies of the digestive system.