The causes of anal distension mainly include internal hemorrhoids, as well as perianal abscesses and rectal polyps: 1. Internal hemorrhoids can cause anal distension and pain, mainly due to the formation of blood clots or venous blood masses that stimulate the mucous membrane of the intestinal wall, or the edema or congestion of the hemorrhoid nucleus, etc. In the treatment, you can choose potassium permanganate lotion for cleaning and anti-inflammatory around the anus, or you can choose warm water sitz baths to relieve the blood circulation around the anus. The actual pills are usually the same as the ones that are used in the marketplace. 2, perianal abscesses can also cause anal swelling and pain, mainly caused by acute purulent infection of the anal glands. The actual fact is that you can find a lot of people who are not able to get a good deal on this kind of things.