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:

Helicobacter pylori infection: The H. Pylori is a bacterium which is supposed to affect almost half of the world population though the symptoms may not be seen in every affected person. The bacteria break down the mucus lining which results in gastritis. In certain cases, it may also cause ulcerations in the stomach lining.

Drugs: Medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) (which include aspirin, ibuprofen, naproxen, etc.), steroids, cancer medicines, iron supplements, etc. can induce damage to the stomach lining.

After medical procedures such as radiation treatment, surgery on the stomach, any other major surgery, etc.

Infections such as tuberculosis, syphilis; viral, bacterial, fungal (yeast infection) infections, parasites, etc.

Stress can be one of the major causes of gastritis – especially in cases of severe and/or prolonged stress

Major traumatic injury or burns

Excessive use of alcohol

Autoimmunity – here the body's defense attack the body's own cells (in this case the stomach lining)

Pernicious anemia

Chronic reflux of the bile juice from the intestine

Other medical conditions such as Crohn's disease, some connective tissue disorders, kidney failure, liver failure, etc. are also associated with gastritis