Flatulence during chemotherapy for stomach cancer may be caused by uncontrolled bowel movement, stimulation of chemotherapy drugs, electrolyte disorder and so on. 1. Incompatible stool: If patients eat less during chemotherapy for gastric cancer, it will cause long time of persistent stools in the intestinal tract causing incompatible stools, which may lead to symptoms of flatulence during chemotherapy for gastric cancer. 2. Stimulation by chemotherapeutic drugs: As chemotherapeutic drugs may inhibit intestinal peristalsis, therefore, during chemotherapy for gastric cancer, under the stimulation of drugs, intestinal peristalsis will be lowered, which may lead to intestinal flatulence. 3. Electrolyte disorders: During chemotherapy for stomach cancer, a large amount of vomiting liquid may be produced, and electrolytes in the body will be discharged with the vomiting liquid, causing certain ionic disorders, which may also lead to intestinal flatulence during chemotherapy for stomach cancer. When patients have flatulence during chemotherapy for stomach cancer, they need to consult doctor in time and cooperate with treatment actively after detailed examination and determination of the cause of the disease.