Omeprazole

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] 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 that of other PPIs.^[11] It can be taken by mouth or by injection into a vein.^[1][12] It is also available in the fixed-dose combination medication omeprazole/sodium bicarbonate as Zegerid^[13][14] and as Konvomep.^[15]

Common side effects include nausea, vomiting, headaches, abdominal pain, and increased intestinal gas.^[1][16] Serious side effects may include Clostridioides difficile colitis, an increased risk of pneumonia, an increased risk of bone fractures, and the potential of masking stomach cancer.^[1] Whether it is safe for use in pregnancy is unclear.^[1] It works by blocking the release of stomach acid.^[1]

Omeprazole was patented in 1978 and approved for medical use in 1988.^[17][18][19] It is on the World Health Organization's List of Essential Medicines.^[20] It is available as a generic medication.^[1] In 2022, it was the ninth most commonly prescribed medication in the United States, with more than 52 million prescriptions.^[21][22] It is also available without a prescription in the United States.^[23][24]