How did the heartburn happen?
Numerous things can trigger gastritis and it has been associated with several things right from medical conditions to medicines to habits, etc. The primary mechanism by which this occurs is damage to the ‘protective mucus barrier’ of the stomach. This mucus barrier prevents the acid from coming in direct contact with the stomach lining. When the barrier is damaged, the acid causes the lining of the stomach to be inflamed.
Any of the following can act as a trigger for gastritis: