Gastritis can be caused by irritation due to excessive alcohol use, chronic vomiting, stress, or the use of certain medications such asaspirin or other anti-inflammatory drugs. It may also be caused by any of the following:
Helicobacter pylori (H. pylori): A bacteria that lives in the mucous lining of the stomach; without treatment, the infection can lead toulcers, and in some people, stomach cancer.
Pernicious anemia: A form of anemia that occurs when the stomach lacks a naturally occurring substance needed to properly absorb and digest vitamin B12
Bile reflux: A backflow of bile into the stomach from the bile tract (that connects to the liver and gallbladder)
Infections caused by bacteria and viruses
If gastritis is left untreated, it can lead to a severe loss of blood and may increase the risk of developing stomach cancer.