Using Nexium to Treat GERD and Erosive Esophagitis. Gastroesophageal reflux disease, or GERD for short, is a condition in which stomach acids and other contents of the stomach go back into the esophagus. This can result in GERD symptoms, including the most common symptom of GERD -- heartburn. One of the complications of GERD is erosive esophagitis, which develops when the lining of the esophagus become damaged from the stomach acid. Nexium has been licensed to treat symptoms of GERD, including heartburn.