Gastritis is when the lining of the stomach becomes inflamed or swollen. This usually happens after the stomach lining has been damaged. Gastritis that is long-lasting or recurring is known as chronic gastritis. Chronic gastritis is one of the most common chronic conditions and can last for years or even a lifetime if left untreated. A wide range of different conditions and factors are known to cause or contribute to the development of chronic gastritis. Resolving mild cases of gastritis can often be through the use of medication and lifestyle changes.