Glycolic acid peels are contraindicated in certain conditions such as pregnancy, nursing patients, active herpes simplex, contact dermatitis, and patients with glycolate hypersensitivity. Furthermore, they may enhance skin sensitivity to ultraviolet light (Fabbrocini et al. 2012; Fischer et al. 2010).

Glycolic acid aims the corneosome, increasing damage and decreasing cohesiveness, leading to desquamation (Fartasch et al. 1997). AHA superficial peels also increase epidermal activity of enzymes, causing epidermolysis and exfoliation (Fischer et al. 2010). The epidermis becomes thinner, and the multiplication of the epidermal cells results in regeneration and remodeling, with improvement of texture and surface abnormality. Stimulation of the epidermis also leads to the production of cytokines, which activates the fibroblasts to produce collagen type I and type IV and elastin fibers, improving the appearance of photoaged skin. Deeper peels result in a greater deposition of collagen and glycosaminoglycans (Murad et al. 1995).

Concerning acne, it is effective in treating non-inflammatory lesions and inflammatory eruptions because of its antibactericidal effects on Propionibacterium acnes and antioxidant action. It may also improve penetration of topical acne therapies, and thus it may be used as an adjuvant treatment for acne. However, it has very few effects on atrophic or hypertrophic scars (Atzori et al. 1999). By causing epidermolysis, dispersing basal layer melanin and epidermal dermal hyaluronic acid, they can also correct altered keratinization seen in these cases, in addition to improving collagen gene expression through an elevated secretion of IL-6 (Bernstein et al. 2001).

The provider and the patient should keep in mind that multiple peels are usually necessary to obtain optimal results, in average once every 15 days for 4–6 months, until the expected outcome is observed.

The patient should be interrogated about the degree of sun exposure, history of herpes simplex, recent isotretinoin treatment in the last 6 months (for medium-depth GA peel), and tendency for postinflammatory hyperpigmentation. Patients with darker skin type have a tendency to develop postinflammatory hyperpigmentation. Also, a complete medical history and current medications should be informed by the patient.

Informed consent and also photographic record and standard good-quality photographs are highly recommended for all types of peelings.

Written information about the type of the peeling they will be subjected to, what they should expect, and post-care peel is a necessity.

The physician should also explain to the patient the need for multiple procedures to achieve the expected outcome and evaluate the patient’s expectations and motivation. The patient should be advised about the recovery time, importance of maintenance regimens after the peel, and possible side effects and complications (Khunger 2008).

Performing the peel requires consideration of the following steps: skin preparation, cleansing, application, and neutralization.

It is imperative that the patient maintain a rigorous skin care regimen during the immediate preoperative and postoperative periods in order to obtain the most favorable results. The physician should be prepared to provide guidance, sources, and examples that help formulate this regimen.

The patients should have their skin treated with products like retinoic acids, AHAs, and sometimes bleachers for 2–4 weeks prior to the peel and discontinue 3–5 days before the procedure. Thus, patients may be primed at home by using mild topical peeling agents such as tretinoin 0.025%, adapalene 0.1%, glycolic acid 6–12%, kojic acid, or azelaic acid (Khunger 2008).

The use of tretinoin prior to chemical peeling amplifies the procedure’s effects. By decreasing the stratum corneum’s thickness, it increases the peel’s depth. Tretinoin is also known to reduce healing time after resurfacing.

Hydroquinone (2–4%) is useful in patients with skin type III or higher, as it blocks the tyrosine enzyme and decreases epidermal melanin production during preoperative and healing periods, even without history of pigmentary abnormalities (Monheit and Chastain 2012).

The choice of the primer agent will depend on the need of each patient and risk of complications. The same primer agent may be used for maintenance afterward.

Cleansing the skin before a chemical peel is extremely important to obtain a homogeneous penetration of the peel and thus a uniform result. First, the patient is asked to wash the face with soap and water. Then, the skin surface must be mildly cleansed to remove any remaining traces of makeups or oils. Isopropylic alcohol is used to clean the skin and acetone for degreasing.

The patient should be seated in a comfortable position, wearing a hair cap, and must keep their eyes closed during the entire procedure. The acid can be applied with gauze pads, fan brush, gloved fingers, or a cotton-tipped applicator, depending on the formulation of the peel. In general, gel formulations have a slower penetration time and are easier to control (Fabbrocini et al. 2009).

It is better to start applying the glycolic acid on the forehead and then to the rest of the face since the forehead is less sensitive and can tolerate a little more exposure to the acid than other parts of the face can. Very sensitive areas, like the corners of the nose and lips, should be protected with Vaseline. Training is necessary for the application of this peel, since the whole skin should be exposed to the acid in the same amount of time, and the risk of excessive penetration is high when the provider is not familiar with the procedure (Ditre et al. 2006). The depth of penetration of the peeling agent can be observed and controlled by the changes in the skin color: