The most common causes of gastritis are:
- Aspirin or anti-inflammatory drugs, such as ibuprofen.
- Infection of the stomach with Helicobacter pylori (H. pylori)
- Erosion of the protective layer of the stomach lining
Less common causes of gastritis are:
- Eating or drinking caustic or corrosive substances (such as poisons)
- Backflow of bile into the stomach (bile reflux)
- Autoimmune disorders (such as pernicious anemia)
- Excess gastric acid secretion (such as from stress)
- Viral infection, especially in people with a weak immune system
Gastritis can occur suddenly (acute gastritis) or gradually (chronic gastritis).