Enteritis is when the intestine — the long tube that carries food through the body after the stomach — becomes infected or swollen and sore. It can hurt, and it often brings diarrhoea, cramps, and a need to stay near a toilet. Doctors use this word; family talk is more often “a stomach bug,” though that phrase is looser and may mean the stomach, the intestine, or both. Dirty food or water is a common cause, especially when you travel. If the stomach is involved as well, the longer name is gastroenteritis, which you will hear more often than enteritis alone.