The standard adult dose of omeprazole is 20 mg once a day, whether you’re taking the over-the-counter version or a prescription. Higher doses are used for specific conditions, but for most people, 20 mg daily is both the starting point and the upper limit without a doctor’s direction.
OTC vs. Prescription Doses
Over-the-counter omeprazole comes in 20 mg delayed-release tablets. The labeled instructions are straightforward: one tablet every 24 hours, taken in the morning at least one hour before eating, for 14 consecutive days. You can repeat that 14-day course every 4 months, but you should not take it for longer than 14 days or more frequently than that unless a doctor tells you otherwise.
Prescription omeprazole is also typically 20 mg once daily, but the treatment window is longer. For GERD without visible damage to the esophagus, a standard course runs up to 4 weeks. If there’s erosive esophagitis (where stomach acid has actually worn away tissue in the esophagus), the course extends to 4 to 8 weeks. Some people with confirmed, complicated reflux disease stay on 20 mg daily as ongoing maintenance therapy under medical supervision.
When Higher Doses Are Prescribed
For rare conditions where the stomach overproduces acid, such as Zollinger-Ellison syndrome, the dosing picture looks very different. The starting dose is 60 mg once daily, and doctors may increase it well beyond that. The FDA label notes that doses as high as 120 mg three times daily have been administered in these patients. When the total daily amount exceeds 80 mg, it’s split into multiple doses throughout the day rather than taken all at once.
Omeprazole is also sometimes prescribed twice a day as part of combination therapy to treat H. pylori infections, the bacteria responsible for many stomach ulcers. In that context, the twice-daily dosing is short-term and paired with antibiotics.
Why Timing Matters
Omeprazole works by shutting down acid-producing pumps in the stomach lining. Those pumps are most active when you eat, so the medication is most effective when it’s already circulating in your system before a meal. Taking it 30 to 60 minutes before breakfast gives it time to absorb and reach peak levels right when your stomach ramps up acid production. Swallowing it with food or after a meal reduces how well it works.
If you’re on a twice-daily prescription dose, the second dose is typically taken before dinner, following the same logic.
How Long Is Too Long?
The 14-day OTC limit exists for a reason. Omeprazole is meant to heal, not to be used as a daily antacid indefinitely. The American College of Gastroenterology recommends an initial PPI course of 8 weeks for GERD, after which a doctor should evaluate whether continued use is appropriate. The American Gastroenterological Association goes further, recommending that if you’ve been on a PPI for 12 months without a confirmed diagnosis of GERD, your doctor should reassess whether you still need it, potentially with endoscopy and reflux monitoring done while off the medication.
That said, some people genuinely need long-term therapy. Patients with Barrett’s esophagus, severe erosive esophagitis, a history of esophageal ulcers, or peptic strictures are generally advised to stay on PPIs rather than stop them. The decision to discontinue should be based on whether there’s still a valid reason to take it, not on fear of side effects alone.
Risks of Extended or High-Dose Use
Because omeprazole suppresses stomach acid, long-term use can interfere with the absorption of certain nutrients. The most established concerns are magnesium, iron, vitamin B12, and calcium deficiencies. Reduced calcium absorption is the proposed mechanism behind a modestly increased fracture risk seen in some studies. There’s also a recognized increase in the risk of intestinal infections, particularly C. difficile, since stomach acid normally helps kill ingested bacteria.
You may have seen headlines linking PPIs to dementia, kidney disease, or heart attacks. Those findings came from observational studies that couldn’t prove cause and effect. Higher-quality research has not confirmed those associations, and the American College of Gastroenterology’s 2022 guidelines specifically note that the apparent links were likely coincidental rather than causal. The one risk that holds up consistently across studies is the increased susceptibility to gut infections.
Dosing for Children
Pediatric omeprazole dosing is weight-based. Children weighing 5 to under 10 kg receive 5 mg once daily. Those between 10 and under 20 kg get 10 mg once daily. Children over 20 kg, and teens 17 and older, take the standard adult dose of 20 mg once daily. These doses apply to prescription use for GERD and erosive esophagitis. OTC omeprazole is not intended for children under 18 without a doctor’s guidance.
If You Have Liver Problems
Omeprazole is processed by the liver, and people with significant liver impairment may clear the drug more slowly, leading to higher-than-expected levels in the body. Expert recommendations call for a dose reduction in these patients, though exact adjusted doses haven’t been formally studied. Kidney impairment, on the other hand, does not require a dose change.
If your current dose isn’t controlling your symptoms, taking more on your own isn’t the right move. Persistent heartburn or reflux despite 14 days of OTC omeprazole is a signal that something else may be going on, and a prescription evaluation can determine whether you need a longer course, a different dose, or a different approach entirely.