What is acid reflux disease? Acid reflux disease can and often is mistaken for heartburn. But the heartburn symptoms of acid reflux disease usually occur 2 or more days a week for at least 3 months and can damage your esophagus. At the top of your stomach is a muscle called the lower esophageal sphincter (LES), which normally opens and closes allowing food to enter? It also prevents the acid in your stomach from backing up into your esophagus.
