Generally speaking, irregular stools with sour odor are considered to be caused by dyspepsia, colitis and other intestinal inflammation, intestinal flora imbalance, and so on. 1. Indigestion: too little exercise, overeating, eating too much cold and stimulating, greasy and hard food such as ice cream, spicy hot, etc., increase the burden on the gastrointestinal tract, can cause indigestion such as bloating, abdominal pain, diarrhea and other symptoms, but also can cause an imbalance in the gastrointestinal tract flora, which may cause the stool is not shaped with a sour smell. 2. Intestinal inflammation: bacteria, fungi, viruses and other inflammatory diseases of the colon, abdominal pain, persistent diarrhea, pus and blood stools, loss of appetite, loss of weight and other symptoms. Such as Crohn’s disease, mucus, pus and blood stools, acute and severe sensation; ulcerative colitis, to the right lower abdominal pain, can be accompanied by pasty stools and so on. 3. Imbalance of intestinal flora: it can be related to environmental factors, mental and psychological factors, improper diet, etc. It can cause indigestion and other symptoms, unformed stools with sour odor, and may also lead to diarrhea and constipation alternately, and other symptoms. Unshaped stool with sour smell may also be caused by intestinal tuberculosis, intestinal tumors, etc. It is recommended to consult a doctor in time to clarify the diagnosis and carry out targeted treatment.