Acid reflux disease or, more properly, gastroesophageal reflux disease (GERD) is a digestive system disorder where stomach acid splashes on the bottom of the esophagus. It is typified by a severe burning sensation in the chest, usually after meals, usually several times a week. Although it is not particularly dangerous, it can be a chronic problem and can lead to damage to the esophagus and even esophageal cancer.