Prilosec (omeprazole) is used to treat acid reflux, gastritis and peptic ulcer disease. It belongs to a class of drugs called proton pump inhibitors (PPIs).
PPIs such as Prilosec work by reducing the production of stomach acid. With less acid in the stomach, the irritation to the lining of the esophagus, stomach and upper intestine decreases. And the inflamed areas can heal.
You should ideally take Prilosec on an empty stomach before meals. But even when you take it right after eating, its still very effective at blocking acid.
What time of day you take Prilosec doesn't matter as long as you are not experiencing symptoms. For most people, one dose every 24 hours is sufficient. But some people need to take Prilosec twice per day, around every 12 hours, to get full relief.