Chemical Peels

What are Chemical Peels

Chemical peels involve the application of solutions to the surface of the skin to remove layers of skin cells and to stimulate the growth of new skin. Removal of the external layer of the skin also allows enhanced penetration of agents applied to the skin topically following the peel. For this reason a chemical peel may enhance the results of other cosmetic procedures.

Types of Chemical Peels

There are essentially three types of chemical peels: superficial, medium and deep (Table 1).

Superficial chemical peels penetrate to the depth of the upper epidermis, or superficial layer of the skin. They are generally safe and when performed over a period of time can produce exceptional results. Superficial peels are often referred to as “lunchtime” peels, as they are generally tolerated exceptionally well and essentially require no downtime following the procedure. The deeper the peel, the more dramatic the immediate results, however, the risk of significant side effects and length of recovery time increases proportionally. These side effects include including scarring, infection and temporary or permanent changes in skin colour. Medium and deep chemical peels are performed in a monitored environment by a physician.

Multiple factors affect the depth of the peel. These factors include the chemical agent itself (Table 1), the concentration of the agent, pre-treatment of the skin prior to the peel, the region of the face (some regions more responsive than others), sebaceous gland number and activity and procedural techniques such as defating the skin before the peel and mode of application of the peel.

Table 1: Classification of Peels

*TCA= trichloracetic acid

What a peel can and can’t do

Studies have demonstrated that chemical peels are safe and have multiple proven benefits (BOX 1). However, there are certain things a peel will not achieve (BOX 2).

BOX 2:

Men Benefit from Chemical Peels as well

Men are now just as likely to have chemical peels as women. It has recently been demonstrated that men are three times more likely to develop skin cancer. It is also well known that men stay out in the sun longer than women and thus men's skin is more photodamaged and aged than women. Chemical peels may improve or reduce some of this photoageing. In addition, chemical peels are effective for the management of razor bumps or pseudofolliculitis barbae.

Superfical Peeling Agents

The most common superficial peeling agents are hydroxy acids. Hydroxy acids are a group of weak organic acids that stimulate epidermal cell shedding by dissolving the lipid cement-like substance that bonds the epidermal cells together. This accelerates cell renewal within the basal or bottom layer of the epidermis and stimulates synthesis of new collagen. In addition, hydroxy acids absorb moisture from the atmosphere and increase the plasticity of the stratum corneum. There are two types of hydroxy acids - Alpha Hydroxy Acids (AHA’s) and Beta Hydroxy Acids (BHAs).

There are multiple different types of AHA’s.

Glycolic acid (derived from sugar cane) is the most commonly known AHA, but it is now generally recognized that lactic acid is a better performing hydroxy acid.

Lactic acid (derived from sour milk) is gentler, less irritating, has a higher therapeutic index and hence level of effect than glycolic acid when used as a peeling agent. It also has additional benefits such as increasing skin ceramide or lipid content as well as skin moisture content. A lactate concentration equivalent to 8% lactic acid also achieves a significant lightening effect on the skin by the inhibition of tyrosinase. This is popular for clients of Asian decent. This whitening effect is thought to be more significant than that achieved by other popular bleaching agents including liquorice, kojic acid and arbutin. Lactic acid peels are hence considered suitable for patients with sensitive skin, acne or those with darker skin complexions.

Mandelic acid (from bitter almond) is a newer AHA that was originally used as an anti-bacterial agent. It is marketed as being less irritating than glycolic acid and is thought to be effective for the management of acne.

A number of important factors influence the effectiveness of AHA’s (Table 2).

TABLE 2: Factors influencing the effectiveness of AHA’s

The popularity of beta hydroxy acids within professional peels is increasing. BHA’s are lipid (oil) soluble (whereas AHAs are water soluble) and therefore penetrate into the pores and fatty layers of the skin more effectively. The most common BHA in cosmetic products is salicylic acid (or related substances, such as salicylate, sodium salicylate, and willow extract, beta hydroxybutanoic acid, tropic acid , trethocanic acid). Salicylic acid is a popular agent used in acne products and is rapidly gaining momentum as an effective peeling agent. Salicylic acid peels are thought to be better for dark or Asian skin than glycolic acid peels, as they are less likely to cause post-inflammatory hyperpigmentation.

Mixing lactic acid (AHA) and salicylic acid (BHA) in a ratio of 2:1 is thought to result in a pronounced synergistic effect leading to a sharp increase in cell renewal and a drop in irritation. These peels are called combination hydroxyl acid peels (CHA’s) or alphabeta hydroxyl peels.

Polyhydroxyacids and bionic acids are an emerging breed of hydroxyacid. These have been developed and commercialized by one particular cosmetic company and are reported to antioxidant properties in addition to all the traditional benefits of AHA’s. They are also considered to be less irritating.

Beyond the realm of AHA’s and BHA’s there are a variety of less comercialised peels. The advantages and disadvantages of these agents is outlined in Table 3.

TABLE 3 Non-hydroxy acid Superficial Peeling agents

*TCA: Trichloracetic acid

Side Effects of Superfical Peels

A recent study of 286 patients who underwent eight weekly superficial peels demonstrated that almost all patients tolerated superficial peels well. Minor side effects included mild discomfort, burning, irritation and mild short lived redness. There was an extremely low incidence of major side effects in this study.

Despite having a good safety profile, superficial peels do have potential side effects (Box 3).

Peeling following a superficial peel is generally mild and usually is not visible. This peeling can be controlled with the use of light moisturising agents. Post-inflammatory hyperpigmentation (increased pigmentation) or hypopigmentation (decreased pigmentation) is an unlikely side effect following a superficial peel. It is more common in those with darker complexions. Scarring is an extremely unlikely event if a superficial peel is carried out by a trained practitioner.

Chemical peels increase the sensitivity of the skin to UV damage. Full sun protection and sun avoidance is necessary following the peel. Some studies have shown that AHA’s can increase UV damage potential by up to 30% in the first 48 hours following a peel.

BOX 3: