The stomach naturally produces acid to digest food.  Sometimes this acid flows back and digestive enzymes clog the esophagus.  When this occurs frequently, it is called gastro-esophageal reflux disease (GERD), which commonly causes heartburn. Acid can also make its way up the esophagus and into the throat, a condition called Laryngopharyngeal Reflux (LPR).  LPR often occurs without heartburn, making it difficult to diagnose, and is often considered a "silent" disease.  Symptoms include hoarseness, chronic throat clearing or cough, sore throat, a feeling of something caught in the throat, excessive mucus, difficulty swallowing, and restless sleep. A small amount of reflux is normal.  Abnormal amounts left untreated can lead to damage in the throat, upper airway, lungs, vocal cord nodules. It can also cause airway narrowing, granulomas and even cancer.