May Be Caused by

 Common

Acute gastritis

Aspirin

Crohn disease

Helicobacter pylori infection

Hyperacidity

NSAID

Peptic ulcer

Steroid medication

 Uncommon

Candidiasis

Corrosive gastritis

Cryptosporidium antritis

Cytomegalovirus infection

Herpes simplex

Multiple endocrine neoplasia syndrome

Postoperative gastritis

Radiation therapy

Zollinger-Ellison syndrome