Perianal diseases, as well as many systemic diseases, can cause blisters around the anus, especially hemorrhoids, perianal abscesses, and sexually transmitted diseases. First, hemorrhoids can cause blisters around the anus, mainly due to varicose veins around the anus, which are mostly red or brown in color and can cause significant pain and swelling around the anus. Secondly, perianal abscess can also form blisters around the anus, and there is a large amount of pus in the blisters, which can cause severe itching and redness around the anus. In addition, sexually transmitted diseases, represented by acrodermatitis vulgaris, can also cause blisters around the anus, and some of these blisters may break and ulcerate, and are somewhat contagious.