Application of most peeling agents is similar. Before application, the skin to be treated is first cleansed with acetone or alcohol. Because most chemical peels are lipophobic, this facilitates greater depth and promotes even distribution of the peel. The peel is carefully applied to the subunits of the face with gauze or a cotton-tipped applicator. To ensure a consistent effect, it is important to apply the chemical evenly and avoid pooling of the agent on the face. The peel should be delicately blended with the neighboring untreated skin by feathering the edges to prevent a discrete line of demarcation.

16.3.4 Superficial Peels

Superficial chemical peeling is an exfoliation of the stratum corneum or entire epidermis to promote epidermal regrowth with a more rejuvenated appearance. Superficial chemical peeling is a treatment with many benefits and few risks or side effects. It can be performed on individuals of all ages, as early as ages 25–30, when the first effects of photoaging become evident. Superficial chemical peels can minimize fine lines resulting from sun damage, acne, and rosacea. Repeat superficial peels may be required to achieve optimal effects. Patients must be counseled that multiple superficial peels do not equal a medium or deep chemical peel. Superficial peeling agents include alpha hydroxy acids such as glycolic acid 20–50%, salicylic acid, Jessner’s solution, and 10–30% TCA.

16.4 Alpha Hydroxy Acids

Alpha hydroxy acids (AHAs) have been used for thousands of years to improve the appearance of the face. Cleopatra herself is rumored to have used the debris of the bottom of wine barrels for facial rejuvenation. AHAs function by promoting keratinocyte discohesion in the granular cell layer; causing increased cell turnover. Commonly used AHAs are derived from fruit and dairy products, such as glycolic acid from sugar cane, lactic acid from fermented milk, citric acid from fruits, tartaric acid from grapes, and malic acid from apples. Glycolic acid is currently the most commonly used AHA.

The efficacy and penetrating depths of AHAs are dependent on their concentration, the vehicle, and the pH. Over-the-counter AHA products containing 3–10% glycolic acid or other naturally occurring organic acids cause exfoliation over several weeks and may be used as a pre-peel primer to potentiate the effects of higher concentration peel procedures or other resurfacing modalities.

Professional grade AHA peels are usually 50% or higher. Unlike other peeling agents, penetration of alpha hydroxy acids is time dependent. The time to peel is dependent on both the concentration and the pH of the acid. Higher concentrations and lower pH’s require shorter peeling periods. The alpha hydroxy acid peel is applied with a sponge or gauze, systematically proceeding from one facial region to another. After placement of an AHA preparation, the skin becomes erythematous. The mild stinging and redness typically disappears 1 h after treatment. Development of a white frost is not a desirable outcome of an alpha hydroxy acid peel as it denotes penetration depth into the dermis. Removal of the agent is achieved by rinsing with water or neutralization with an alkaline solution such as sodium bicarbonate. Deeper than intended peeling may occur if neutralization is not performed within the correct time. The subsequent exfoliation takes place over a few days and reepithelialization is usually complete within 7–10 days. Multiple treatments may be required to achieve the desired results and should be spaced several weeks apart to allow epidermal recuperation. Alpha hydroxy acid peels produce the least profound results of the chemical peeling agents; however, they are associated with the lowest frequency of complications.

AHAs, such as glycolic acid, can also be mixed with facial cleaners or creams in lesser concentrations as part of a daily skin-care regimen to improve the skin’s texture or maintain results following a resurfacing procedure.

16.5 Salicylic Acid

Beta hydroxy acids, also known as salicylic acids, provide a safe, mild rejuvenation to skin. Salicylic acid functions via keratolysis, is lipid soluble, and has a predilection for sebum-containing cells making it an excellent peel for comedonal acne. In addition to acne,