Anal swelling and burning may be caused by anal papillitis, ulcerative colitis, rectal prolapse, hemorrhoids, perianal abscess and other reasons. 1. Anal papillitis: dry stools, anal intercourse and other factors lead to anal papilla damage rupture, secondary bacteria and other infections, anal papillae congestion and hypertrophy, surface inflammatory substances oozing, so there will be symptoms of anal swelling and burning. 2. Ulcerative colitis: ulcerative colitis involves the rectum, sigmoid colon, intestinal mucosa non-specific inflammatory reaction, ulceration, bleeding and other lesions, so there will be symptoms of anal swelling and burning. 3. Rectal prolapse: the mucosa of rectum or the whole layer of rectum moves down and prolapses below the dentate line under the action of external force, which leads to the increase of local pressure in the anus, and the feeling of anal distension and burning sensation in the case of concurrent infection. 4. Hemorrhoids: rectal and anal areas of submucosal supportive tissues such as submucosal venous plexus congestion and enlargement, resulting in local intestinal lumen protruding, defecation increases the pressure on the hemorrhoids, and thus the appearance of blood in the stool, anal swelling, itching sensation, burning sensation and other symptoms. 5. Perianal abscess: the soft tissues around the rectum and anal canal and the surrounding cavity of the tissue after bacterial infection of purulent inflammation, purulent secretions accumulate to form an abscess, resulting in the anus part of the local mucous membrane bulge, so there will be anal swelling and burning and other symptoms. Anal swelling and burning may be related to a variety of factors, it is recommended that the patient consult a doctor for a clear diagnosis.