Can omeprazole cause nausea after eating?

Yes, but consider...: Omeprazole decreases acid in your stomach. If there is acid damage to the stomach lining, then Omeprazole speeds healing. If your response to Omeprazole has been disappointing then either: 1) the dose is too low; 2) there is significant damage that needs a longer time to heal; 3) your problem is not acid-related and further investigation is warranted. Call your doctor and discuss your next step.