Heartburn is a burning sensation in the upper abdomen or behind the sternum caused by the reflux of acidic stomach contents into the esophagus. It often occurs after eating, when bending forward, or in a supine position.
Heartburn is most commonly associated with gastroesophageal reflux disease (GERD), increased gastric acidity, or dysfunction of the lower esophageal sphincter. Symptoms may improve with changes in diet and eating habits; however, frequent or persistent heartburn requires medical evaluation.