It also closes to keep the stomach contents out of the esophagus. If this sphincter weakens or relaxes, the contents of the stomach splash back up into the esophagus. This splashing is known as gastroesophageal reflux. GERD causes burning pain under the breastbone or in the upper abdomen, often called heartburn. This pain may increase when eating, bending over, or lying down.
Antacids usually relieve the pain.
Pain may increase at night or cause a person to wake up during the night. GERD can be caused by a weak esophageal sphincter that is present at birth or that develops later in life. Hiatal hernia is a condition in which the stomach pushes up into the diaphragm muscle. When this happens, the esophageal sphincter does not work properly. As a result, the fluid can easily leak back into the esophagus.