The three main symptoms of anal fissure are pain, blood in stool and constipation. Anal fissure is caused by dry stool that cracks the skin around the anus, which makes the skin around the anus particularly sensitive, thus triggering spasm of the anal sphincter, so the patient will have paroxysmal pain after defecation, which often lasts for several hours and is relieved only when the anal sphincter is tired, and the pain is intense, showing a knife-like pain, and the same pain will be triggered by defecation again. Blood in the stool is caused by a fissure around the anus, which is difficult to heal because of the presence of spasm of the anal sphincter and poor blood supply around the fissure, as well as an ulcerated surface at the edge of the fissure. Dry stool, which is constipation, is caused by pain during defecation triggering the patient’s fear of constipation, and the patient will subconsciously suppress the urge to defecate causing dry stool, which will stimulate the anus and produce severe pain. This is a vicious circle in which constipation and anal fissure interact with each other and can further aggravate anal fissure.