Carbon 13 Breathalyzer test should be preceded by dietary abstinence, discontinuation of some medications (with time requirements), and some diseases for which the test is not recommended. 1. Before the test, you should maintain a fasting state or have fasted for at least 2 hours. 2. Ensure that acid-suppressing drugs (e.g., omeprazole, pantoprazole) have been discontinued for at least 2 weeks before the test. 3. Ensure that antibiotics and bismuth agents (e.g. cephalosporins, amoxicillin, bismuth potassium citrate) have been discontinued for at least 4 weeks prior to the test. 4. For the review of the effectiveness of H. pylori treatment, the breath test should be repeated after 10 to 14 days of regular medication and 1 month after stopping the medication. 5. If the patient has obvious gastrointestinal dynamics or structural abnormalities (e.g., severe bile reflux, after major gastrectomy), it will increase the probability of false-negative results, so theoretically, it is not recommended that such patients undergo this test. 6. Carbon 13 breath test is not suitable during gastrointestinal bleeding.