Breath testing generally refers to the carbon breath test, which is not affected by diet, and is generally accurate 1.5 hours after a meal if no medication is taken. Carbon breath test is mainly used to diagnose H. pylori infection, currently more commonly used is the carbon 14 breath test, the test is not affected by diet, so it is also possible to carry out H. pylori test after meals. However, if the patient is taking antibiotic drugs, acid-suppressing drugs and gastric mucous membrane protectants, such as amoxicillin, roxithromycin, omeprazole, bismuth potassium citrate, etc., it may affect the test results to some extent. Before blowing test 1.5 hours after meal, make sure that you are not taking drugs that affect the test results, if you are taking drugs, you generally need to stop taking drugs before testing.