Heartburn and acid reflux are often used interchangeably. However, they are two different conditions: Heartburn is a symptom of acid reflux or GERD (gastroesophageal reflux disease), and is caused by acid entering the esophagus and causing a burning sensation. Acid reflux is the actual movement of the acid from the stomach into the esophagus. It is not always accompanied by heartburn, but it can cause other symptoms such as coughing, hoarseness, difficulty swallowing, and chest pain. Heartburn is usually experienced in the middle of the chest, while acid reflux is usually more severe and can reach up to the throat. Treatment for heartburn and acid reflux may include lifestyle changes, medications, or surgery depending on the severity of the condition.