It feels like there are always small worms in the anus, which can be considered to be caused by pinworms, localized pruritus or hemorrhoids and other etiological factors. 1. Pinworm disease: the host is mostly children, in the night sleep, the anal sphincter muscle relaxation, female worms will crawl out of the anus to ovulate, causing itching of the perianal skin, can also be seen in the perianal white thread-like worms. 2. Localized pruritus: anal pruritus is its most common type, which can be in the range of the anus nearby, and can also be accompanied by perineal itching. Chili and other spicy food stimulation, dyes, etc. can cause anal pruritus, or in proctitis, the anus and perineum secretions stimulate perianal can also cause perianal pruritus. 3. Hemorrhoids: If external hemorrhoids occur, it can cause anal moisture and anal discomfort, perianal secretions and moist factors will stimulate the perianal skin, causing itching. When there are symptoms of discomfort around the anus, you need to consult a doctor in time, and follow the doctor’s instructions after the diagnosis is clear.