Anal swelling is a common symptom in anorectal medicine, and its causes can be complex. Many diseases can cause anal swelling, including: 1. Inflammation of the anorectum is one of the most common causes. When there is inflammation in the intestines, rectal congestion and inflammation can lead to anal swelling; 2. Infectious diseases around the anus, such as perianal abscesses, especially submucosal abscesses inside the anus can cause significant swelling; 3. Foreign bodies or masses in the anorectum, the most common being rectal tumors, when the tumor is too large and presses around the anorectum can create a feeling of anal swelling; 4. Prolapsed anal diseases, including rectal prolapse or severe prolapsed hemorrhoids can cause anal swelling; 5. Clinically, it is also common to encounter anal swelling without any physical signs, which may be neurosis. The specific cause of anal swelling must be examined by a specialist in anorectal medicine at a regular hospital so that the corresponding disease can be identified and ruled out and treated accordingly.