Constipation alternating with diarrhea may be related to irritable bowel syndrome, intestinal tuberculosis or colon cancer. 1. Irritable bowel syndrome (IBS): it is a functional intestinal disease, the pathophysiological mechanism may be related to abnormal gastrointestinal dynamics, mental and psychological disorders, intestinal infections, etc. It has the characteristics of abdominal pain accompanied by changes in bowel habits, and part of the population may suffer from diarrhea and constipation alternately. 2. Intestinal tuberculosis: most of the causes of intestinal tuberculosis can be related to laryngopharyngeal tuberculosis or open pulmonary tuberculosis caused by swallowing bacterial sputum. At the onset of the disease, there can be abdominal pain, change of bowel habit or systemic symptoms (e.g. low-grade fever, night sweating, anemia, malaise, etc.), etc., and some people can have diarrhea and constipation alternately. 3. Colon cancer: it is a malignant tumor of gastrointestinal tract, with no special symptoms in the early stage, but after development, it can cause changes in bowel habit and shape of feces, such as increase in frequency of bowel movement, diarrhea, constipation, blood in feces, abdominal pain, abdominal mass, etc. For those who have long-term changes in fecal character, they may suffer from abdominal pain, constipation, diarrhea and constipation. For people with long-term changes in stool characteristics, it is recommended to go to the hospital specialist in time, according to the clinical manifestations as well as fecal routine, colonoscopy and other related examinations, after a clear diagnosis, the cause of the symptomatic treatment.