The reasons for exfoliating dry skin are different from the ones for treating oily, blemishprone skin, though the objective is the same: removing dead skin cells that are not shedding normally. Skin can be dry for many reasons, including lack of moisture, a buildup of dead skin cells that don’t easily shed, and abnormal skin cells that adhere together in a way that prevents normal exfoliation and normal moisture retention. (Dry-looking skin can also be caused by moisturizers that are too emollient and hold dead skin cells in place, preventing healthy shedding. When this happens, the surface of the skin feels “greasy” or moist, and the underlying layer feels dry.) When you help dry skin shed dried-up, dead skin cells, it can make room for plumper (moisture-filled), less-dry skin cells to come to the surface, which can lend a fresher look to the skin. This also allows moisturizers to more easily penetrate the skin because there are fewer dried-up skin cells in the way to block absorption.
Exfoliating helps the dead, surface-skin cells shed at a more normal rate, making room for the lower layers of newer skin cells. And for dry skin it is also helpful to efficiently remove dead skin cells to reduce the chance of pores becoming clogged and creating blackheads and whiteheads.