Itchy skin on the buttocks may be caused by: 1. ringworm, mainly due to fungal infection, treatment can be oral terbinafine hydrochloride tablets, topical naftifine ketoconazole cream or bifenbuterol cream applied twice a day; 2. allergic dermatitis, mainly due to contact with chemical fiber or cashmere underwear or allergies caused by contact with poor quality body wash, treatment can be oral epinastine hydrochloride capsules, topical mometasone furoate cream mixed with bupropion cream applied twice a day, during treatment also need to avoid contact with beef, mutton, seafood and alcoholic beverages.