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What Causes Heartburn?

The discomfort and pain of heartburn is caused when the lining of the esophagus, also known as the food pipe, comes into contact with digestive enzymes and stomach acid for an extended period of time.

The muscles at both ends of the esophagus, called esophageal sphincters, relax to let food pass, then tighten to keep stomach acid down. When the lower esophageal sphincter (LES) malfunctions and does not tighten enough, acid can wash up or "reflux" from the stomach into the esophagus, causing heartburn.

Some people also suffer from heartburn or chest pain due to a hiatal hernia, which is an opening in the diaphragm that allows a portion of the stomach to protrude into the chest.