From a medical point of view, acid reflux is a condition caused by acidic contents from the stomach moving upward into the esophagus, which results in a burning sensation. When the valve found at the lower end of the esophagus is dysfunctional, it allows the acidic content of the stomach to be regurgitated, where it would block this behavior when functional.

Another belief is that acid reflux is caused by an individual's eating habits. As the civilized world eats more and more junk and processed foods, the majority of the food ends up in the stomach undigested. This undigested material turns into acidic waste, which causes stomach spasms. These spasms create stomach gas which pops open the valve between the stomach and esophagus, allowing the acidic content to return to the esophagus.

Others believe that acid reflux is related to aging. As we age, the activity of the stomach is reduced. This also reduces the ability to produce hydrochloric acid. The result is the stomach turning into a breeding ground for infection which can cause stomach pain and acid waste irritation.