The test for H. pylori infection requires an empty stomach and at least two hours of fasting, and eating will affect the accuracy of the test. Therefore, it is recommended that patients stop eating after dinner the day before and come to the hospital the next day on an empty stomach for the test, or if they do eat the next day, they are also required to fast for at least two hours before entering the H. pylori test. The most common and simplest method used in clinical practice is the breath test, whether it is the C-13 or C-14 breath test, which requires the patient to fast for more than two hours. The test starts with blowing an air pocket, and then after oral administration of the contrast agent, another air pocket is blown at an interval of half an hour, and then the changes in the two air pockets are observed to determine whether the patient has H. pylori infection. Therefore, the patient is still required to have an empty stomach, because the examination of the digestive tract routinely recommends that the patient be seen on an empty stomach, not only for the blowing of air.