Farting with bad odor is considered to be related to indigestion, constipation, gastroenteritis, intestinal cancer and so on. 1. Indigestion: If you have recently consumed a large amount of high-fat, gas-producing food or have irregular meals that lead to indigestion, you are prone to farting and smelling bad. 2. Constipation: Poor dietary habits, poor defecation habits are the causes of constipation. Constipation patients will have a reduced number of bowel movements, defecation difficulties, dry feces and other symptoms, which can also be manifested as farting and very smelly. 3. Gastroenteritis: the disease is related to microbial infection, reflux of digestive juices, stress reaction and so on. Typical symptoms of patients include epigastric pain, diarrhea, abdominal distension, nausea and vomiting, postprandial fullness, etc. Farting and stinking phenomenon can also occur due to gastrointestinal tract dysfunction. 4. Intestinal cancer: it belongs to malignant tumors, which can also cause some patients to have farting and smelly phenomenon. The cause of intestinal cancer is not yet clear, it may be related to heredity and long-term improper diet, etc. Typical symptoms of patients include change of bowel habit, abdominal pain and abdominal mass. Typical symptoms of patients include change in bowel habit, abdominal pain, abdominal mass, etc. Gallbladder and pancreatic lesions may cause gastrointestinal dysfunction, which may also induce some patients to fart and smell bad. It is recommended to consult a regular hospital for examination in order to clarify the cause of the disease and then follow the doctor’s prescription medication.