Canadian Dermatologist Dr Sahar Ghannam explores the best chemical peeling approaches to achieve a positive aesthetic outcome in darker skin

Chemical peeling is the application of one or more exfoliating agents to the skin resulting in a controlled wound and destruction of one or more parts of the epidermis and/or dermis, the peel results in a re-growth of a new portion of the skin. They have several different indications, but the common treatment goal is to affect a clear, bright and youthful complexion. However, the benefits seen with chemical peels vary in different ethnic and racial groups, and executing an optimal cosmetic peel in darker skin can be a lot more challenging than one may first suppose.

Chemical peeling in darker skin is an art, and there are some pearls on how to best achieve a positive aesthetic outcome in darker skin.

The Fitzpatrick skin classification system links skin color to a response to UV light, a connection that is beneficial since it is known that skin color determines a patient´s suitability for skin rejuvenation procedures. Fitzpatrick skin types I-III have been considered the ideal skin types for these procedures, while types IV-VI have been considered the more difficult types because of the high incidence of post-inflammatory hyperpigmentation and the possibility that the procedure will permanently change the skin color. Since most of the global population, according to the National Geographic, is of skin of color, then most of the world according to this classication cannot be treated by chemical peels! Again the classification did not look at the ethnic background nor the climate.

“The practitioner must keep in mind that a 100% safe chemical peel or procedure does not exist, however the risk can be significantly lowered with procedures that give the physician more control of the variables associated with the peel. Control of the variables can lead to more predictable acid penetration depth, thus increasing the likelihood of good results and avoidance of complications”.

The indications for a superficial peel can either be acne, an uneven complexion – hyperpigmentation/ melasma, prevention/treatment of photo-aging, and maintenance between two sessions of a deeper peel. The peels that are likely to work best in darker skin include TCA 10-35%, glycolic acid 30-70%, salicylic acid 20-30% in ethanol or paste, Jessner solution, retinoic acid, phytic peels, Vitamin C peels and combination peels.

Controlling the peel variables is paramount in attaining a successful cosmetic result in order to avoid post eruptive pigmentation, which is a common and nuisance problem in darker skin types.

TCA Peels

The TCA is the gold standard for all chemical peels. The most important variable in the quality of outcome and safety of a TCA peel procedure is the depth of acid penetration.

Accurately assessing the skin type, as well as pre- and post-op skin condition also play a vital role in outcomes. TCA peels in concentrations of 10%, 35%, and 50% have been classified as superficial, medium, and deep, respectively, with the erroneous assumption that a certain concentration penetrates to a certain depth. TCA concentration determines only the speed at which the acid penetrates the skin, higher concentrations penetrating faster. Any concentration can be made to penetrate at any depth. The therapeutic and caustic effects of TCA are directly related to their concentration.”

The peel in dark skin consists of a weak concentration of TCA (15%-20% m/m), a base solution, and a post-peel mask. The addition of the right amount of 50% TCA in the base solution can transform it into a 15-20% m/m adjuvanted and stabilized TCA. TCA self-neutralizes by combination and denaturalizes skin proteins, producing a peeling effect, improving penetration of the post peel mask and creating dermal stimulation.

TCA can be combined with ascorbic acid/citric acid (which enhance and impart uniformity to the penetration of the TCA), cocamides (which protects the skin and improves the efficacy of saponines), or Na Laureth Sulphate (surface active emulsifying and wetting agents).

TCA does not need to be neutralized, as it is self neutralizing, but a post-peel cream or mask with strongly antioxidant promotion cream can be applied. It immediately stops the burning sensation as a result of the TCA applied, conferring a much-desired soothing effect to the skin. Also, the cream promotes post-peel healing and expedites the healing time.

Combination Peels

One peel that improves melisma, which is a very common problem in darker skin types, is a combination peel that comes as a paste or mask pe ( Azelaic acid, Kojic acid, Phytic acid, Vitamin C, and Retinoic acid), – can either be applied on the first day for 6-8 hours or on the first day for 4-5 hours, followed by a 2-3 hour application weekly. Then a cream with the same ingredients but with less concentration is applied twice a day for two weeks (at least 3 hours/application), then once a day for at least a year, then another peel could be performed.

B- hydroxyl acids, Salycilic acid peel in concentration of 20-25 % in Ethanol, is one of the most useful peels used in any skin type for the management of acne vulgaris , it is performed once every 10 to 14 days . Salycilic acid does not need to be neutralized, it is self neutralized.

Although salycilic acid peels cannot be performed on large areas of the skin as salycilic acid is toxic and can cause salycilism.

Glycolic Peels

As for Alpha hydroxyl acids, and the best known is the glycolic acid which is the smallest of all hydroxyl acids. The mechanism of action of glycolic peels, used in concentrations of 50-70%, is not fully understood, but they are believed to thin the stratum corneum and thicken the stratum granulosum.

Whether the therapeutic effects are merely a result of ph induced irritation has not been demonstrated. This acid affects an uneven peel and if the physician is not careful, a deeper penetration into the dermis can occur if it is not monitored or neutralized properly, especially in thin skin. Here, cases of significant irritation and hypertrophic scarring have been reported.

“Repeated glycolic peels have been said to improve surface texture, superficial hyperpigmentation, acne and xerosis, as well as fine wrinkles. Glycolic acid can be used alone or in combination with other chemicals in some facial peels.

Between peels, before and after the peels the patient should apply daily home care creams like moisturizers and anti-oxidant Vitamin E creams, anti-acne and anti-aging creams, as well as sun-block, so as to optimize the positive cosmetic outcome.

Chemical peels are cheap procedures that every dermatologist and dermatologic surgeon can master, knowing which peel is suitable to use for the patient.