Esomeprazole, most commonly sold as Nexium, is a PPI that is used to treat many stomach conditions including upset stomach, indigestion, peptic ulcer disease, gastroesophageal reflux disease, and Zollinger-Ellison syndrome. It is available in twenty to forty-milligram capsules. It is usually taken once or twice a day. It can sometimes be administered intravenously as well. The pharmaceutical company AstraZeneca manufactures Nexium.