Breath test is not allowed with 1 capsule of oral omeprazole. Breath test is not recommended for any oral omeprazole taken in the last 2 weeks and may lead to false negative results. Breath test is a commonly used method to detect the presence or absence of H. pylori infection, and the appropriate precautions need to be clarified before the test in order to increase the accuracy of the test results. For example, it is necessary to keep fasting or at least have fasted for 2 hours before the test; it is recommended to stop the use of proton pump inhibitors (such as omeprazole) for at least 2 weeks, and stop the use of bismuth, antibiotics and other drugs for at least 4 weeks; eradication of the treatment of Helicobacter pylori for 10-14 days need to be discontinued for 1 month before retesting, and so on. In conclusion, omeprazole should be discontinued for at least 2 weeks before the test is performed before the breath test is performed, otherwise a false negative result may occur.