There are a couple of ways to remove the skin's horny layer to reveal the glowing, living cellular layer beneath. Hydroxy acids, either in the form of beta or alpha hydroxy acids, chemically degrade the physical structure of the cornified cells. With this structure disintegrated, your skin has an easier time shedding these dead cells. Exfoliants hasten the process of shedding dead keratinocytes. They commonly use granules with a crystalline structure, like sugar or salt, which scrub the dead cells from the epidermis.
These methods remove much of the horny layer, but speeding up the desquamation process too often can actually damage the skin or make existing damage worse.
A cell dies after it has divided a set number of times -- a process called apoptosis. Following apoptosis, a cell stops functioning, but remains intact. Other cells in the body destroy and remove the cellular debris from the body. The cell structure, contents and the DNA found in the cell nucleus are broken down and enveloped by microphages, which prevent this organic waste from being reabsorbed by the body. In other words, most dead cells are little more than physiological trash.
Skin cells, however, appear to be unique. The dead keratinocytes actually serve to protect the layers beneath. Instead of being absorbed by microphages and carried away from the body following apoptosis, the cells dry out and harden, becoming cornified and offering a layer of defense for the thriving keratinocytes below. This horny layer has been shown to protect skin from damaging ultraviolet rays from the sun [source: Gordon and Fugate].
On a more immediate scale, daily exfoliating can damage skin. Hydroxy acids can irritate keratinocytes once the horny layer is removed. The abrasive granules found in exfoliating scrubs can also harm skin.
Instead of exfoliating every day, you can slough off dead skin by gently using a scrub once a week. If you use a hydroxy acid, then once a week is about as often as you should apply it [source: Flamberg]. If your skin continues to feel irritated, you should stop using these products. Of course, as with most things, you might want to consult a dermatologist before beginning an exfoliating regimen.