There are generally 4 kinds of drugs to kill H. pylori, and there are more kinds of drugs, some patients will have many uncomfortable symptoms after using the drugs, such as abdominal pain and diarrhea, bitter mouth, black stool, rash, etc.. Black stool is what will appear after taking bismuth, you can not care about it, you can get better after stopping the drug for some time. Many people will feel bitter in the mouth after taking Clarithromycin. If there is abdominal pain and diarrhea, rash and other uncomfortable reactions, it is recommended to first exclude other causes of discomfort, if the symptoms are not serious, you can take the drug again for observation, if the symptoms worsen or the patient can not tolerate, you can stop the drug. However, because stopping the medication will bring about the loss of the therapeutic effect of all the drugs taken earlier, and if it is necessary to take the medication again to kill the bacteria, it is hoped that the patient can continue to take the medication as long as it is tolerated.