Rennie medicine for the treatment of gastroesophageal reflux, bitter taste in the throat, persistent dry cough, pain when lying down, difficulty swallowing, heartburn, and indigestion, which is pain in the upper part of the intestine that can resemble gas or bloating. Rennie treats stomach or duodenal ulcers, which are ulcers that affect the lining of the stomach, small intestine, or esophagus.