The symptoms of itching at the anal opening often have a variety of causes. Generally speaking, it is divided into the following causes. The first one is perianal skin eczema. After eczema appears on the perianal skin, it produces paroxysmal itching of the skin of the anal opening and the perianal skin, often accompanied by flushing of the perianal skin and the appearance of scattered papules, along with loss of skin pigmentation. The second is neurodermatitis of the anal skin. Neurodermatitis often causes paroxysmal anal pruritus and is accompanied by thickening and pigmentation of the skin at the site of the lesion. The third one is internal hemorrhoids. Internal hemorrhoids tend to secrete too much mucus, which causes dampness at the anal opening, and the damp environment at the anal opening often causes bacterial fungal parasitism, which stimulates itching of the skin at the anal opening.