There are many possible reasons for having a hard stomach after taking medication for Helicobacter pylori: side effects of medications, gastritis, gastric ulcers, and functional dyspepsia. 1. Drug side effects: Helicobacter pylori infection is generally treated with drugs such as omeprazole, metronidazole, amoxicillin, colloidal bismuth pectin. Omeprazole, metronidazole, amoxicillin may appear digestive discomfort, if abdominal pain and other side effects of the symptoms are not very obvious, it is recommended to continue to take the drug, in the discontinuation of the drug one month after the re-examination of Helicobacter pylori. 2. Gastritis, gastric ulcer: If the patient is infected with Helicobacter pylori, in addition to the existence of gastritis, gastric ulcer and other diseases, after taking the drug may be aggravated, resulting in abdominal pain, it is recommended to seek medical advice as soon as possible, gastroscopy, a clear diagnosis. 3. Functional dyspepsia: Functional dyspepsia will appear abdominal distension, abdominal pain and other conditions, gastroscopy did not find organic lesions. Taking the treatment of Helicobacter pylori medicine stomach is very difficult and painful, there are other reasons, it is recommended to go to the regular hospital in a timely manner to improve the examination, to clarify the cause of the disease, by the professional doctor to guide the use of medication, so as to avoid delays in the condition.