Chemical peels are a valuable yet underutilized treatment in dermatology, providing consistent clinical outcomes and high patient satisfaction at low overhead cost. During the 2024 Pigmentary Disorders Exchange Symposium, Dr. Seaver Soon, a Mohs micrographic surgeon and cosmetic dermatologist from San Diego, shared his expertise on superficial and medium-depth chemical peels, highlighting their techniques, benefits, and applications.
Overview of Chemical Peels
Chemical peels are classified based on the depth of injury they induce:
Superficial Peels: Target the epidermis and utilize agents like alpha hydroxy acids (AHAs), beta hydroxy acids (BHAs), Jessner’s solution, retinoic acid, and trichloroacetic acid (TCA) at concentrations of 10-35%. Superficial peels are effective for treating acne and improving skin texture and pigmentation. Superficial peels must be repeated every 2-4 weeks for approximately 4-6 treatments for optimal results.
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- AHAs are hydrophilic, with glycolic acid often preferred in aqueous forms for predictable penetration. AHAs must be neutralized.
- BHAs are lipophilic and thus ideal for acne-prone skin as they can penetrate pores and clear comedones.
Medium Depth Peels: Penetrate the papillary and upper reticular dermis, most commonly as sequential peels where a superficial peeling agent or physical agent is applied first and then followed by TCA 35%. The classic sequential medium depth peels are Jessner’s solution followed by TCA 35% (Monheit peel), dry ice followed by TCA 35% (Brody peel), and glycolic acid 70% followed by TCA 35% (Coleman peel). Medium depth peels achieve results after 1 treatment.
Deep Peels: Penetrate the mid-reticular dermis, using phenol-croton oil emulsions or high concentration TCA (80-100%).
The depth of histologic injury determines the clinical indication. For example, superficial peels are ideal for enhancing skin texture, while medium-depth peels are used for treating actinic keratosis, lentigines, fine wrinkles, acne scars, and pigmentary dyschromia.
Clinical Techniques and Endpoints
Dr. Soon discussed his specific techniques and visual endpoints for various peels:
Glycolic Acid Peels and other AHAs have a time-dependent, rather than a visual, endpoint, typically neutralized with sodium bicarbonate or water after 1-2 minutes. If the patient experiences “hot spots” (focal erythema, burning, or frost), immediate neutralization is necessary to prevent over-penetration and complications.
Tretinoin Peels also have a time-dependent endpoint, as they are washed off 4-6 hours after application. Tretinoin peels address acne, skin texture and pigmentary dyschromia.
Salicylic Acid Peels (20-30%) are available in two types of vehicles: hydroethanolic (HA) and polyethylene glycol (PEG). The HA-based peel produces a crystal precipitate called pseudofrost, which is the clinical endpoint, and is followed by skin peeling. Dr. Soon prefers formulations in PEG because it allows patients to continue their daily activities without experiencing the desquamation while still benefiting from the peel (Lee, 2019).
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- The PEG-based peels slow the delivery of salicylic acid into the skin, which prevent salicylism. Therefore, these peels are good for large surface areas such as the back with acne. He recommends leaving it on for 10 minutes then removing it with dampened washcloths followed by sunscreen.
TCA Peels (10-35%) can vary from superficial to medium depth based on concentration, number of coats, and degree of pressure applied. A speckled frost with background erythema indicates a superficial peel. More coats and pressure can result in a solid white frost, indicating a medium depth peel with penetration into the papillary dermis. The standardized TCA preparation is weight to volume, and neutralization is not needed (Lee, 2019).
To achieve medium depth peels with predictable and reliable results, Dr. Soon recommends classic sequential peels. He suggests starting with a superficial agent like Jessner’s solution followed by TCA 35% to achieve consistent penetration into the papillary dermis. Alternatively, for a deeper medium-depth peel, particularly useful for field precancerization or in male patients, use of a physical agent such as dry ice (solid CO2) followed by TCA 35% offers dependable and effective dermal penetration.
Histologic Effects of Peels
Dr. Soon reviewed research showing that all types of peels stimulate collagen synthesis within the first 14 days in mice subjected to UVB-induced aging. However, only medium and deep peels demonstrated significant long-term improvements in collagen and dermal thickness (Han, 2011). Studies have also indicated that even superficial peels, such as those with glycolic acid, enhance dermal and epidermal hyaluronic acid, suggesting interaction between the epidermis and dermis (Bernstein, 2001; Brody, 1986).
Chemical Peel Indications, Safety and Complications in Skin of Color
Chemical peels are particularly effective for treating melasma, post-inflammatory hyperpigmentation (PIH), acne-induced scarring, and even maturational hyperpigmentation in skin of color. The greatest evidence for treating melasma is with glycolic acids, while the greatest evidence of treating PIH and acne scars is with salicylic acid (20-30%). Dr. Soon prefers to use modified Jessner’s solution in patients with skin of color due to its reduced risk of irritation, and consequently post-inflammatory hyperpigmentation, by using citric acid in place of resorcinol (a known contact irritant).
A study on 473 superficial chemical peels in Fitzpatrick skin types III to VI revealed low complication rates, mostly limited to crusting, PIH, and erythema, which resolved within eight months. Complication rates were higher in skin type VI and lower during winter months (Vemula 2018). Medium-depth peels also show low complication rates, but Dr. Soon advises caution when using them in patients with frontal fibrosing alopecia (FFA) to prevent delayed healing and scarring—a concern that he notes will be highlighted in an upcoming publication by Dr. Felipe Ribeiro from Brazil. Similar risks have already been documented with deep chemical peels (Landau, 2024). In his practice now, Dr. Soon carefully examines patients for FFA before proceeding with medium or deep peels. He notes that patients with FFA have dysfunctional hair follicles, leading to delayed healing not only on the frontal scalp but also on other facial areas, such as the cheek and mandible.
Dr. Soon recommends that patients prime their skin 2-4 weeks before the peel by using a retinoid with low irritation potential, such as adapalene, and hydroquinone, along with a tinted mineral sunscreen, to decrease the risk of post-inflammatory hyperpigmentation. For medium depth peels, during the procedure he informs patients that they may experience a burning sensation lasting about five minutes and prescribes valacyclovir 1g daily for seven days. In the interest of antibiotic stewardship, he does not prescribe empiric antibiotic prophylaxis but prefers to treat based on culture and sensitivity in the event of an infection. Once the procedure is completed, he counsels patients that there should be no pain; if pain persists, it may indicate an infection or early signs of scarring, which can be managed with high potency topical/ intralesional steroids and pulsed dye laser.
In summary, superficial and medium-depth peels are powerful tools in dermatology, offering significant clinical improvements in skin texture, pigmentation disorders, and acne scars. Dr. Soon encourages dermatologists to explore chemical peeling techniques further by joining the International Peeling Society (https://www.peelingsociety.com/) and incorporating these treatments into their practices for enhanced patient outcomes.
REFERENCES
Lee KC, Wambier CG, Soon SL, et al. Basic chemical peeling: Superficial and medium-depth peels. J Am Acad Dermatol. 2019;81(2):313-324. doi:10.1016/j.jaad.2018.10.079
Han SH, Kim HJ, Kim SY, Kim YC, Choi GS, Shin JH. Skin rejuvenating effects of chemical peeling: a study in photoaged hairless mice. Int J Dermatol. 2011;50(9):1075-1082. doi:10.1111/j.1365-4632.2010.04712.x
Bernstein EF, Lee J, Brown DB, Yu R, Van Scott E. Glycolic acid treatment increases type I collagen mRNA and hyaluronic acid content of human skin. Dermatol Surg. 2001;27(5):429-433. doi:10.1046/j.1524-4725.2001.00234.x
Brody HJ, Hailey CW. Medium-depth chemical peeling of the skin: a variation of superficial chemosurgery. J Dermatol Surg Oncol. 1986;12(12):1268-1275. doi:10.1111/j.1524-4725.1986.tb01066.x
Vemula S, Maymone MBC, Secemsky EA, et al. Assessing the safety of superficial chemical peels in darker skin: A retrospective study. J Am Acad Dermatol. 2018;79(3):508-513.e2. doi:10.1016/j.jaad.2018.02.064
Landau M, Tosti A, Kroumpouzos G, Eims E, Goldust M. Frontal fibrosing alopecia-A new absolute contraindication for deep chemical peels. Clin Dermatol. Published online June 27, 2024. doi:10.1016/j.clindermatol.2024.06.024
This information was presented by Dr. Seaver Soon during the 2024 Pigmentary Disorders Exchange Symposium. The above session highlights were written and compiled by Dr. Sarah Millan.
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