GERD stands for gastroesophageal reflux disease, and it’s the condition where acid in the stomach refluxes back into the esophagus. The esophagus is the tube that connects our mouths to our stomachs. When we have a reflux of acid contents into the esophagus, it can cause painful symptoms. Over time, that acid content can even damage the lining of the esophagus and cause additional problems for patients.