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 is a medication that treats conditions that cause too much stomach acid like heartburn, stomach ulcers and reflux disease. It works by reducing the amount of acid in your stomach. It can take several days before your stomach pain gets better after taking this medication. What is this medication? Omeprazole is used to treat certain conditions where there is too much acid in the stomach. It is used to treat gastric and duodenal ulcers, erosive esophagitis, and gastroesophageal reflux disease (GERD). GERD is a condition where the acid in the stomach washes back up into the esophagus. Omeprazole (Prilosec) is a proton pump inhibitor (PPI) that is used to reduce the amount of acid in your stomach and it can be bad for your kidneys. It can cause acute kidney injury and may also worsen the progression of chronic kidney disease (CKD). Prilosec is the brand name for omeprazole, a proton pump inhibitor (PPI) that reduces stomach acid production. Brand-name Prilosec and generic omeprazole contain the same active ingredient and are both widely available. They’re used to treat heartburn and gastroesophageal reflux disease (GERD). Omeprazole (Prilosec) is used to treat symptoms of gastroesophageal reflux disease (GERD) and other conditions involving excessive stomach acid. Omeprazole (Prilosec) is used to treat symptoms of gastroesophageal reflux disease (GERD) and other conditions involving excessive stomach acid. Prilosec is a proton pump inhibitor that decreases the amount of acid produced in the stomach. Prilosec is used to treat symptoms of gastroesophageal reflux disease (GERD) and other conditions caused by excess stomach acid. PRILOSEC is indicated for short-term treatment of active duodenal ulcer in adults. Most patients heal within four weeks. Some patients may require an additional four weeks of therapy.