Heartburn is an uncomfortable feeling or burning pain behind the breastbone. It may occur after eating, soon after lying down, when bending forward, or after taking certain medicines.

Heartburn occurs when stomach acid backs up (refluxes) into the tube that leads from the mouth to the stomach (esophagus), causing pain or discomfort behind the breastbone, in the center of the chest, and occasionally in the back of the throat. Sometimes there may be a sour or bitter taste in the mouth.

Antacids or other nonprescription medicines (such as acid reducers or acid blockers) may relieve heartburn.

Heartburn can be a symptom of gastroesophageal reflux disease (GERD).