Glycolic Acid Peels

Glycolic acid is an AHA, which belongs to a class of naturally occurring compounds derived from food sources such as sugar cane [23]. Glycolic acid peels range in concentration from 20–70% glycolic acid. This type of peel is generally performed every 3–4 weeks for a total of four to six treatments. Glycolic acid peels are indicated in the treatment of melasma, postinflammatory hyperpigmentation, mild photoaging (Glogau I and II), and acne. Glycolic acid peels are generally well tolerated by all skin types I–VI. Several studies have shown that up to 70% glycolic acid is well tolerated with minimal adverse effects and has shown improvement in melasma and postinflammatory hyperpigmentation [24, 25]. Glycolic acid peels may be used as monotherapy, combined with a topical preprocedure rejuvenation regimen consisting of tretinoin and hydroquinone, or even combined with 5-fluorouracil (5-FU) known as the fluor-hydroxy pulse peel for the treatment of actinic keratosis with an improved overall cosmesis [26].

Glycolic acid has been shown to cause discohesion of keratinocytes at low concentrations of 20–40% and causes epidermolysis at higher concentrations 50–70% [27]. Very low concentrations of glycolic acid peels cause an injury limited to the stratum corneum and only creates exfoliation, but the injury may extend into the stratum granulosum. The higher potency glycolic acid formulations injure the entire epidermis down to the basal layer. In contrast to beta-hydroxy acid (e.g., salicylic acid), AHAs are lipophobic in nature. A previous study by Moy et al. demonstrated that glycolic acid has a stimulatory effect on collagen production in fibroblasts. This increased collagen stimulation in normal dermal fibroblasts may account for the production of a new zone of collagen in the upper dermis that would replace the elastotic deposits that form from photodamage [28]. This proposed mechanism may account for the decrease in fine wrinkling, leading to improvement of fine rhytids.


The major factors that determine whether glycolic acid peels result in desquamation or epidermolysis are the concentration of the acid, the pH, the degree of buffering or neutralization with sodium bicarbonate, the vehicle formulation, the frequency of application, the conditions of delivery, the amount of acid delivered to the skin over a given period, and most importantly, the length of time that the acid remains on the skin [7].Prior to the application of the wounding agent, the face must be cleansed to remove any preexisting debris and cutaneous lipids with alcohol or acetone-soaked sponges. Then the agent is applied in any cosmetic unit order, covering the face within 20 s (forehead, cheeks, chin, nose, and upper lip) with large cotton swabs, sable brush, or 2" × 2" gauze pads. The time of application is critical for glycolic acid as it must be rinsed off with water or neutralized with 5% sodium bicarbonate 2–4 min after application.

Postprocedure regimen should include the use of sunscreen, avoidance of excessive sun exposure, and the daily application of a moisturizer. The advantage of this superficial peeling agent is that it only causes mild irritancy, and minimal time is needed for recovery. Patients may return to their normal level of daily activities and can wear makeup to conceal erythema. Complications with glycolic peels are very rare.

Treatment of AK with a superficial peel is best approached by combing 5-FU and glycolic acid. A study conducted by Marrero and Katz found that the use of the fluor-hydroxy pulse peel applied in a pulse dose regimen not only provides cosmetic improvement but, more importantly, has a therapeutic effect on ablating premalignant AKs [26]. The ability of AHAs to eradicate AKs is variable and depends on peel depth [29]. 5-FU is an antimetabolite that inhibits DNA and RNA synthesis and destroys hyperproliferative AKs [30].A major limitation in the use of daily 5-FU topical regimen is severe erythema, local irritation, and discomfort associated with the treatment period of 4–8 weeks [31]. However, it has been shown that weekly pulse dosing of 5-FU is equally efficacious at treating facial AKs as the conventional treatment regimen without the severe side effects [32]. Therefore, the study conducted by Marrero and Katz [26] hypothesized that the use of 5- FU with AHAs (glycolic acid) would work synergistically to improve cosmesis as well as treat AKs. This study found there was a dramatic reduction in the number of AKs, which was sustained at 6 months follow-up after the fluorhydroxy pulse peel side of the face, with 92% reduction in AKs versus 20% for the glycolic acid side alone. In addition, there was also a significant cosmetic benefit to the combination peel.