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] Learn about the side effects of omeprazole, from common to rare, for consumers and healthcare professionals. Prescription omeprazole comes as a delayed-release (releases the medication in the intestine to prevent break-down of the medication by stomach acids) capsule, and packets of delayed-release (releases the medication in the intestine to prevent break-down of the medication by stomach acids) granules for suspension (to be mixed with liquid) to take by mouth or give through a feeding tube. Find patient medical information for Omeprazole (Prilosec, Prilosec OTC) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings View omeprazole information, including dose, uses, side-effects, renal impairment, pregnancy, breast feeding, monitoring requirements and important safety information. Most people can safely take omeprazole for a few weeks, depending on why you’re taking it. Learn about long-term use of omeprazole here. NHS information about the medicine omeprazole, including what it's used for, who can take it, how to take it and side effects. Omeprazole is a medication that reduces the amount of acid in your stomach. It treats heartburn, stomach ulcers and reflux disease. Omeprazole is a proton pump inhibitor that is used to treat symptoms of gastroesophageal reflux disease and other conditions caused by excess stomach acid. 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.