Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Gastroesophageal Reflux Disease (GERD)

What Is It?

Gastroesophageal reflux disease, commonly called GERD, is a digestive disorder in which the stomach's juices (acid and digestive enzymes) flow backwards, or reflux, into the esophagus. The esophagus is the tube that carries food from your mouth to your stomach. The lining of the esophagus can't handle these caustic substances, so the esophagus becomes inflamed. This causes heartburn and other symptoms. If GERD is not treated, it can permanently damage the esophagus.

A muscular ring seals the esophagus from the stomach. This valve is called the esophageal sphincter. Normally, this muscular ring opens when you swallow, to let food into your stomach. In between swallows or belches, it squeezes tight to prevent food and acid in the stomach from backing up into the esophagus.

In most people with GERD, the esophageal sphincter does not seal tightly. It remains relaxed between swallows and allows digestive juices to move up into the esophagus and irritate the esophageal lining. Certain foods, smoking, alcohol, pregnancy and many medications can weaken or loosen the lower esophageal sphincter. Increased abdominal pressure, because of obesity or pregnancy, can push against the sphincter, forcing it open. It is also possible for the sphincter to loosen if a bulge in the stomach, called a hiatal hernia, protrudes above the diaphragm.

Prolonged exposure to acid can cause the esophagus to become inflamed (esophagitis), to become more narrow (strictured), or to develop an open sore (ulcer) in the esophagus. Long-term exposure to acid also can lead to a condition called Barrett's esophagus, in which the normal gray-pink tissue of the esophagus is replaced by salmon-colored tissue that looks more like the lining of the stomach. Barrett's esophagus leads to cancer of the esophagus in 2% to 5% of people with the condition.

About 17 million people in the United States have heartburn and other symptoms of GERD. For many of these people, heartburn is not merely an occasional discomfort that follows a rich meal; it is a frequent, even daily, ordeal.