Omeprazole, sold under the brand names Risek and Omezole, among others, is a medication used in the treatment of gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger–Ellison syndrome.[1] It is also used to prevent upper gastrointestinal bleeding in people who are at high risk.[1] Omeprazole is a proton-pump inhibitor (PPI) and its effectiveness is similar to other PPIs.[7] It can be taken by mouth or by injection into a vein.[1][8]

Common side effects include nausea, vomiting, headaches, abdominal pain, and increased intestinal gas.[1][9] Serious side effects may include Clostridium difficile colitis, an increased risk of pneumonia, an increased risk of bone fractures, and the potential of masking stomach cancer.[1] It is unclear if it is safe for use in pregnancy.[1] It works by blocking the release of stomach acid.[1]

Omeprazole was patented in 1978, and approved for medical use in 1988.[10] It is on the World Health Organization’s List of Essential Medicines.[11] It is available as a generic medication.[1] In 2019, it was the eighth most commonly prescribed medication in the Pakistan.