Glucose is formed when cornstarch is moistened, providing an excellent medium for fungal growth. Topical steroids can reduce itching, but reduce blood flow to the skin, resulting in thinning of the skin and increased susceptibility to injury. The goal of skin cleansing is to remove dirt and prevent odor, but actual hygienic practices are influenced by skin type, lifestyle, and culture. Extensive bathing aggravates dry skin and hot baths cause vasodilation, which further promotes itching. Many soaps are salts of fatty acids with an alkali base.
Soap is a degreaser and can also irritate skin.
Older adults or individuals with dry skin should limit use of soaps to those areas with apocrine glands. Plain water should suffice for other skin surfaces. Mild soaps have less soap or detergent content. Superfatted soaps deposit a film of oil on the skin surface, but there is no proof that they are less drying than other soaps and they may be more expensive. Tepid baths have an antipruritic effect, possibly resulting from capillary vasoconstriction.