Acid reflux or gastroesophageal reflux (GER) occurs when the acidic contents of the stomach seep back up into the esophagus, the muscular tube that carries food from the mouth to the stomach. The acid can damage the esophagus, causing pain or discomfort. GER is common and when it occurs, it often causes a bad taste in the back of the mouth. Refluxed stomach acid can also cause a burning sensation in the chest or throat called heartburn or acid indigestion. When persistent acid reflux occurs more than twice a week it is called gastroesophageal reflux disease (GERD). In addition to chronic heartburn, over time GERD can lead to more serious health problems.

Most people have occasional episodes of acid reflux (GER) while heartburn symptoms occur weekly in as many as 20% of the population. GERD with daily heartburn symptoms affects an estimated 10% of Americans at any one time and may occur in as many as 35% of the population in their lifetime.