Itchy skin around the anus (pruritus ani) can have many causes.After bowel movements, the anal area should be cleaned with absorbent cotton or soft, plain toilet or facial tissue, which may be moistened with warm water. Frequent dusting with cornstarch or talcum powder helps combat moisture. Corticosteroid creams, antifungal creams such as miconazole, or soothing suppositories may be used. Foods that can cause anal itching are avoided for a while to see whether the condition improves. Clothing should be loose, and bed clothing should be lightweight. If the condition does not improve and a doctor suspects cancer, a skin specimen may be obtained for examination.
Resource: Merck Manual Home Edition