In general, the eighteen-year-old boy stool is not shaped by eating too much cold food such as ice cream and other dietary factors caused by physiological phenomena, this situation is a normal phenomenon; may also be caused by ulcerative colitis, intestinal tuberculosis and other pathologic phenomena, this situation is not normal phenomena. 1. Physiological phenomenon: Eating excessive spicy stimulation, cold and greasy food, such as spicy hot, alcohol, strong tea, ice cream, etc., can stimulate the gastrointestinal mucosa, aggravate the burden on the gastrointestinal tract, resulting in gastrointestinal dysfunction, causing abdominal pain, diarrhea (stools do not form) and other symptoms. 2. Pathological phenomena (1) Ulcerative colitis: it is an autoimmune disease with limited or extensive ulcerative lesions in the intestinal tract as the main pathological changes, which may cause abdominal pain, diarrhea, bloody stools, mucus stools and other symptoms, and may also be accompanied by anemia, emaciation, electrolyte disorders and other symptoms. (2) Intestinal tuberculosis: it is a granulomatous inflammation caused by Mycobacterium tuberculosis infection of the intestines. In addition to intestinal tuberculosis, patients may have extraintestinal tuberculosis, such as pulmonary tuberculosis, and symptoms such as malaise, low fever in the afternoon, mushy stools, abdominal pain, and diarrhea may occur. Eighteen-year-old boy stool is not shaped suggest timely medical treatment in order to clarify the diagnosis, under the guidance of the doctor for targeted treatment.