Proton pump inhibitors (PPIs) are used to treat gastroesophageal reflux disease (GERD), stomach ulcers, and erosive esophagitis. They also have other uses, such as managing Zollinger-Ellison syndrome. PPIs work by reducing the amount of acid your stomach makes, which helps to relieve symptoms and promote healing. These medications come in different forms, including oral pills and some injectable options. Examples include pantoprazole (Protonix), omeprazole (Prilosec, Prilosec OTC), and esomeprazole (Nexium).