Omeprazole is both an over-the-counter and a prescription medication. The over-the-counter form is used to treat heartburn. The prescription form is used to treat gastroesophageal reflux disease (GERD), certain ulcers, Zollinger-Ellison Syndrome, erosive esophagitis (EE), and infections cause by the bacteria H. pylori. This medication page refers to the prescription form of omeprazole.

Omeprazole belongs to a group of drugs called proton-pump inhibitors, which work by reducing the amount of acid made in the stomach.

This medication comes in capsule form or in packets to be mixed with water to form a liquid. It is taken once or twice daily, one hour before a meal.

Common side effects of omeprazole include headache, stomach pain, and nausea.