Inside scoop: Medium to deep peels of the entire face are rarely done today, because of the risks of scarring. Peels of the upper lip can lighten skin, leaving the appearance of a white "mustache."
Chemical peels are often used to treat scars, pigmentation, and photodamage on the skin's surface. Chemical peels help to minimize the signs of skin damage by sloughing away the superficial surface layers of the epidermis, stimulating the healing process and the generation of fresh, new cell layers. This new cell generation leads to a rejuvenated skin appearance. Salicylic acid, lactic acid, and alpha-hydroxy acid are common agents in chemical peels.
Most chemical peels work on a superficial level to exfoliate (by burning off) the top layers of skin. Peels can go down to the papillary dermis, which is the top part of the dermis. By doing so, a peel removes surface pigmentation (such as brown spots and melasma), smoothes the texture, decreases acne, and even helps firm the skin and reduces the appearance of fine lines. A strong peel, for example a 40% TCA peel, can go deeper into the dermis and cause enough inflammation to set up a wound healing response that can stimulate collagen formation.
There are many types of peels - glycolic acid, retinoic acid, trichloracetic acid - and each has a different interaction with skin proteins and have varying specializations. TCA works on melanocytes; retinoic acid zones in on the sebaceous glands; lactic acid blows up keratinocytes and is an effective exfoliating agent; glycolic also exfoliates but has less risk of causing hyperpigmentation. Your dermatologist will choose the appropriate kind, and the concentration that will be safest and most effective for your particular skin type and conditions.
A higher concentration of acid will go deeper into the skin, disintegrating cells as it moves through. A lot of dermatologists do combination peels, combining two different acids at milder concentrations, rather than doing one super-intense peel, which can cause side effects or complications.
TCA is "melanotoxic," destroying melanosomes that make pigment, so this kind of peel is ideal for treating melasma or superficial discoloration. A moderate chemical peel (20% to 30% TCA or 40% to 70% glycolic acid) is a less expensive way to improve your complexion with almost immediate gratification. It's the poor man's (or woman's, as the case may be) laser. Chemical peels are an effective way to tackle fine lines, dull skin, and sun damage with lots of brown spots. But only a robust (at least 30% TCA) peel will make significant changes to extremely sun-damaged skin with a loss of elasticity.
The sensation during a 30% TCA type of peel (which is moderate to more extreme) rises like a crescendo - like going up a roller coaster, getting to the top, and then making a dramatic descent. The peel has a slow onset; then you begin to feel pinprick tingles, which intensify more and more into thousands of tiny, sharp stings for about six minutes until it gradually calms down. At its worst point, people describe it as feeling like a hot curling iron hitting your face repeatedly.
With a 30% TCA peel, the skin is lobster red for three or four days; then it becomes extremely dry and itchy; and finally it peels for about four days. A milder glycolic peel will leave small, dry, flaky areas, which will wash off in the shower.