Enteritis is an inflammation of the small intestine, often accompanied by inflammation of the stomach (gastritis) and large intestine (colitis), collectively known as gastroenteritis. It can be caused by infections (bacterial, viral, parasitic), certain medications, radiation therapy, or autoimmune conditions. Symptoms typically include abdominal pain, diarrhea, nausea, vomiting, and fever, varying in severity based on the etiology and extent of inflammation. Diagnosis involves clinical evaluation, stool tests, and sometimes imaging or endoscopy.