A proton pump inhibitor called Prilosec reduces the quantity of acid the stomach produces. Prilosec is used to treat problems brought on by an excess of stomach acid, such as symptoms of gastroesophageal reflux disease (GERD). Additionally, omeprazole, the active ingredient of Prilosec, is used to aid in the recovery of erosive esophagitis, which is an acid reflux disease that damages the esophagus.