What is Gastroesophageal Reflux Disease (GERD)?

Gastroesophageal reflux disease (GERD), sometimes simply called reflux, is a condition where acidic stomach contents flow back from the stomach into the food pipe (esophagus). This can happen when the muscular valve between the stomach and the esophagus does not close properly. Occasional reflux is normal,   but if this happens often or for a long time, it can cause troublesome symptoms and injury to the esophagus.