Heartburn is the most common symptom of acid reflux. Your stomach is protected from the corrosive effects of stomach acid. If your lower esophageal sphincter doesn’t prevent your stomach acid from leaking out of your stomach and into your esophagus, you will experience a painful burning sensation in your chest.
Heartburn can range from uncomfortable to painful. However, the severity of the burning sensation doesn’t necessarily indicate lasting or permanent injury to the esophagus.https://www.healthline.com/health/gerd/acid-reflux-symptoms#common-symptoms