How do you heal gastritis? how long does it last for?

Depends on the cause: Gastritis is often associated with H. pylori infection, which can ultimately cause gastric ulcers and even cancer. I recommend Mastic Gum, available from a health food store. Mastic gum kills H. pylori, and heals gastric and duodenal ulcers. It is a great gastric pain reliever as well. Usual dose is 1,000 mg per day for two weeks, but you can take it indefinitely, as it is completely non-toxic