Gastritis is an inflammation, swelling and irritation of the lining of the stomach. The inflammation of gastritis is most often the result of infection with the same bacterium that causes most stomach ulcers. The most common causes of gastritis are regular use of certain pain relievers, drinking too much alcohol, chronic vomiting and stress.

Gastritis may occur suddenly (acute gastritis) or appear slowly over time (chronic gastritis). In some cases, gastritis can lead to ulcers and an increased risk of stomach cancer. The majority of individuals who suffer from gastritis improve quickly with treatment.