Pruritus ani is the term used for intense and protracted itching in the perianal area. Possible causes include parasitic and other infectious disorders (pinworms, fungi, yeast, Streptococcus, and pyogenic infections) and dermatoses (psoriasis, intertrigo, lichen planus, seborrheic dermatitis, lichen sclerosus, neurodermatitis, atopic dermatitis, leukoplakia, Bowen's disease, Paget's disease, and contact dermatitis). Common causes of contact dermatitis include dyes or additives in cleansing tissue, overmedication such as with "caine" derivatives, soap, douches, nail polish, deodorants, perfumes, clothing, and powders. Local factors that can incite itching include hemorrhoids, foreign bodies, cryptitis, and fissures. Additionally, one must consider sensitivities to drugs (such as antibiotics) and foods (particularly spicy foods and condiments). Systemic diseases (hepatic and biliary diseases, lymphoma, pellagra, and diabetes) should also be considered.

Evidence of these conditions in characteristic sites will help establish the diagnosis, as will appropriate testing procedures such as scrapings for tinea or yeast, bacterial culture, clear adhesive tape preparations for pinworms, Wood's light examination for erythrasma, biopsy, and patch testing.