Inflammation in the stomach. Acute gastritis, usually caused by ingesting something irritating or by infection, starts suddenly, with severe pain, vomiting, thirst, and diarrhea, and subsides rapidly. Treatment involves a short fast and then a bland diet, sedatives, and antispasmodics. Chemical gastritis, from ingestion of corrosive chemicals, requires emptying and washing out the stomach. Chronic gastritis has vague symptoms, including abdominal discomfort or pain, poor appetite, gas, and irregular bowel movements. Causes include prolonged use of aspirin or other irritating drugs, infection with Helicobacter pylori, and pernicious anemia. Treatment for chronic gastritis depends on the cause.