Omeprazole is in a category of drugs called proton pump inhibitors (PPIs). These block the production of stomach acid. Available by prescription and over the counter, omeprazole is sold in generic form and under the brand name Prilosec. Most people do not experience any side effects.
Most Common Effects
In clinical trials with omeprazole, as summarised by eMedTV, side effects occurred in between 1 per cent and 7 per cent of participants. These included abdominal pain, back pain, constipation or diarrhoea, upper respiratory tract infections and dizziness.
Less Common Effects
Less common omeprazole side effects include nausea, vomiting, leg cramps, muscle pain, nervousness, weakness and water retention.
Rarely, omeprazole can cause pancreatitis, with symptoms of nausea, fever and chills, significant upper abdominal pain, and a rapid heartbeat.
Hip Fracture Risk
According to a study published in the Journal of the American Medical Association (JAMA) in 2006, long-term therapy with PPIs, including omeprazole, is associated with an increased risk of hip fracture.
Rarely, people experience an allergic reaction to omeprazole. Signs include rash or hives, difficulty breathing, and throat, face or mouth swelling.
Omeprazole interferes with various drugs, including diazepam, warfarin, phenytoin, ketoconazole, digoxin, saquinavir, nelfinavir and atazanavir.