Esomeprazole belongs to a class of drugs known as proton pump inhibitors (PPIs). It is used to treat gastroesophageal reflux disease, peptic ulcer disease, and Zollinger–Ellison syndrome. Esomeprazole decreases the amount of acid produced in the stomach. It works by blocking the proton pump in the stomach’s cells. When the proton pump is blocked, the stomach makes less acid.