NHS information about the medicine omeprazole, including what it's used for, who can take it, how to take it and side effects. Omeprazole: learn about side effects, dosage, special precautions, and more on MedlinePlus Omeprazole is also used to treat dyspepsia, a condition that causes sour stomach, belching, heart burn, or indigestion. In addition, omeprazole is used to prevent upper gastrointestinal tract bleeding in seriously ill patients. Omeprazole is a proton pump inhibitor (PPI). It works by decreasing the amount of acid produced by the stomach. Omeprazole (Prilosec) is a proton pump inhibitor (PPI). Over-the-counter (OTC) omeprazole (Prilosec) can ease heartburn, while the prescription version can treat gastroesophageal reflux disease (GERD) and other conditions involving too much stomach acid. Omeprazole (Prilosec) is taken by mouth, typically once daily 30 minutes before breakfast. Some of the more common side effects of omeprazole. Omeprazole is a proton pump inhibitor used to reduce excess stomach acid in heartburn (GERD), stomach ulcers, duodenal ulcers, erosive esophagitis, and other conditions Omeprazole is a medication that reduces the amount of acid in your stomach. It treats heartburn, stomach ulcers and reflux disease. Learn about the side effects of omeprazole, from common to rare, for consumers and healthcare professionals. Omeprazole, sold under the brand names Prilosec and Losec among others, is a medication used in the treatment of gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger–Ellison syndrome. [1] Find patient medical information for Omeprazole (Prilosec, Prilosec OTC) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Omeprazole reduces the amount of acid produced in the stomach. Acid is produced naturally in your stomach to help you digest food and to kill bacteria.