Techniques to improve the appearance of the skin have advanced as we better understand the skin’s physiology combined with society’s preoccupation with health and physical appearance. Longer life expectancies result in people living longer which leads to more pronounced signs of ageing in the skin as they do so. We now know that ageing in the skin is brought about through a variety of factors. These include genetic changes and hormonal variations (intrinsic ageing) as well as environmental influences like sunlight, dermatological diseases, smoking, alcohol and our eating habits1.
Changes occurring in the skin through intrinsic factors result in dryness, flaccidity, vascular alterations, wrinkles, and a decrease in skin thickness2. Degeneration of elastic fibres and collagen, the appearance of pigmented spots, and the formation of pre-malignant or malignant lesions further attribute to the changes in appearance. Ultra-violet (UV) radiation and the chemical assault on the skin (through using multiple cosmetic products) promotes the formation of free radicals which increases the number of non-localised oxidative lesions. Free radicals alter metabolism and are responsible for premature ageing, which increases the risk of cutaneous cancer2–4. Skin that has not been overly exposed to the sun is characterised by its spotless appearance, homogenous pigmentation, and soft texture. As the years pass, the speed of cellular renovation slows.
Chemical peeling is a procedure that aims to accelerate the process of cutaneous exfoliation and promotes cellular renovation using chemical substances. This is a way in which the skin acquires a more youthful and renewed appearance5.
The process consists of applying one or more caustic agents to the skin to bring about the controlled destruction of the epidermis and upper layers of the dermis, and the re-epithelialisation of the epidermis. The popularity of this procedure is evident as clients achieve an improvement in the appearance of skin, including that of any remaining scar tissue6,7.
Chemical peels are classified into three types: superficial, medium, and deep2.
Superficial peeling acts on the epidermis. Alpha-hydroxy acids (AHAs), beta hydroxy acids (salicylic acid), trichloroacetic acid (TCA), resorcinol, azelaic acid and tretinoin are used as active substances.
Recommended for cases of:
- light photoaging,
- hyperkeratotic eczema (thickening of the keratin in the outer layer of the skin),
- actinic keratosis,
- fine wrinkles, and
Medium peeling acts at the level of the papillary dermis. It can be used with TCA or AHAs.
Deep peeling acts on the reticular dermis. Active ingredients used are TCA at 50% and phenol (Baker/Gordon solution) amongst others.
Recommended for cases of:
- moderate wrinkles,
- keratosis, and
The process of peeling is brought about by the chemical denaturation (coagulation) of the proteins that encounter the caustic chemical substance used in the peel. The denatured protein layer is then rejected through an immune response, which gives the physical appearance of peeling.
Superficial and Medium Peeling
Superficial peeling is epidermal and can be used on all types of skin and in any area of the body. TCA, among numerous other active substances, may be employed in formulas to precipitate medium depth peelings2 in concentrations of 10%–20%.
Alpha-hydroxy acids (AHAs) are part of a group of substances used for superficial peels. AHAs are effective in treating wrinkles, dehydration, thickening and irregular pigmentation of the skin2.
Glycolic acid (GA) is routinely used in cosmetic formulas. Owing to its small molecule size, it has a greater power of penetration in relation to other AHAs. In addition to the concentration used, it is important to consider the pH value of the preparation, which may vary from pH 2.0 to 4.0. The lower (or more acidic) its value, the higher the peel’s exfoliating action. Glycolic acid at pH 3.5 on the skin is ideal for good exfoliation. During the post-treatment peeling phase, it is important to use a sunscreen for better daytime skin protection8.
Although there are several reports about the clinical effects of GA in literature, its biological mechanism remains mostly unclear, and there are only a few reports about its effects on epidermal keratinocytes (the predominant cell type in the outermost layer of the skin). Okano Y et al, at the Kobe University in Japan, investigated the effect of GA on the dermal matrix metabolism of keratinocytes and fibroblasts using in vitro and ex vivo systems. Their results suggest that GA contributes to the recovery of photodamaged skin through various actions, depending on the skin cell type9, 10.
Glycolic acid caused minimal inflammation in the epidermis and upper dermis. However, the collagen deposition caused by the glycolic acid was disproportionately increased suggesting a direct stimulatory effect by the agent11.
Medium peeling is used to remove actinic keratoses, wrinkles, pigmentary dyschromia, or to improve the appearance of scars. The classic chemical agent used for this type of peeling was TCA, in concentrations of 20%. However, TCA has the inconvenience of causing skin problems, such as the appearance of scars and cutaneous hypopigmentation11. Due to this, TCA has been used in combination with other active substances, such as glycolic acid to allow for a smaller concentration of TCA to be needed, therefore avoiding such side-effects. TCA acts on the epidermis and dermis, while its active mechanism works on exfoliation and the destruction of the corneal stratum, which occurs after cellular renewal2,9.
Deep peeling reaches the lower papillary or reticular dermis. The phenol peel is the most popular treatment product for this type of peel. It produces a coagulation of skin proteins and is considered to be a chemical agent producing intense facial rejuvenation when used correctly12. Clinically, phenol produces bacteriostatic effects in minimum concentrations of up to 1%. When above this concentration, it possesses a bactericide action. In the nerve endings of the skin, phenol acts as a local anesthetic12. As a chemical compound, phenol is soluble in oils and fats. In case of accidental contact, it is quickly removable from the skin with glycerine, vegetable oils or 5% ethyl alcohol15. The best-known formula for phenol-based peeling is Baker-Gordon’s (1962) in which phenol is diluted to a concentration varying from 45 to 55%6,13,14.
Deep peeling is recommended for the following cases:
- Bleaching of skin
- Hyperpigmentation or heterogeneous pigmentation
- Acne scars
- Actinic lentigos.
As a precaution, before using phenol peeling, patients who register the following ailments must not be treated:
- existence of heart, kidney and hepatic disease;
- appearance of herpes;
- continual exposure to UV rays;
- recent use of isotretinoin;
- psychological instability;
- predisposition towards keloids; and
- skin types IV to VI in accordance with Fitzpatrick or Glogau classification (including wrinkle types)2,15.
The ideal patient for this type of peeling must have skin that is light in colour, fine and dry, or in other words, individuals with Fitzpatrick skin types I and II with fine wrinkles. Men have thicker skin, which reduces the action of phenol and results in a lower effectiveness of treatment when compared to women15,18. Therefore, it is necessary to use more concentrated formulas or a combination of treatments.
The Fitzpatrick Scale
- hair: red or blond
- eyes: blue, grey or green
- skin: pale white, white with freckles
- burn easily in the sun, never tans
- highly susceptible to premature ageing and skin cancers from UV
- hair: blond, red, light brown
- eyes: blue, grey, green, hazel
- skin: pale white
- burn easily in the sun, tan lightly with repeated exposure
- high risk for skin cancer
- hair: chestnut or dark blond
- eyes: brown, blue, grey, green, hazel
- skin: olive, light brown
- sometimes burns, gradually tans
- skin cancer risk high with extreme exposure
- hair: medium to dark brown
- eyes: brown, hazel
- skin: olive-looking, light to medium brown
- seldom burn, tan easily
- avoid extreme sun exposure to reduce skin cancer risk & pigmentation
- hair: dark brown
- eyes: brown
- skin: olive or dark brown
- tan easily & rarely burn.
- watch out for uneven skin tone & pigmentation from UV exposure
- hair: very dark or black
- eyes: brown
- skin: very dark brown or black
- rarely burn
- watch out for uneven skin tone & pigmentation from UV exposure
Based on the time of onset, complications can be immediate or delayed.
- Immediate (within minutes to hours after peeling)
- Irritation, burning, pruritus and pain
- Persistent erythema
- Delayed (within a few days to weeks):
- Infections (bacterial, herpetic, and candidal)
- Scarring, delayed healing, milia and textural changes
- Hyperpigmentation, hypopigmentation, and lines of demarcation
- Loss of cutaneous barrier and tissue injury
- Acneiform eruptions
- Allergic reactions, toxicity, and ectropion
- Ocular complications
Usually, complications are minor and are more common in dark-skinned individuals. They are seen more in medium and deep peels.
Prevention and treatment of complications
The complications mentioned above are related to problems with infection, inflammation or healing.
Healing is of concern if the treatment was done too deep into the reticular dermis, as with deep peeling. Visible scarring will result, which is permanent. Thoclor’s HOCl Immune Solution, especially the concentrations found in our GF1 Aftercare product, will assist with wound healing as previously discussed. It must be reiterated that HOCl cannot prevent the formation of scars, but it will lead to the earlier maturation of the scar.
With intermediate and light peels HOCl will reduce downtime - faster re-epithelisation and healing will help to get you or your clients back to work in a shorter time.
The disinfectant power of HOCl will assist in preventing infection in the treated area. Start by applying our GF1 product pre-operatively. Post-treatment the area must be sprayed regularly to prevent any contamination with pathogens through touch or exposure to contaminated objects. It is of utmost importance to prevent or treat infection in a chemical peel area as it can lead to permanent scarring or discolouration.
Inflammation post-peeling is a major concern, especially in darker skin types. Acute and chronic inflammation can cause hyperpigmentation - Post Inflammatory Hyperpigmentation (PIH) as it is commonly referred to. The powerful inflammation modulation effect of HOCl will help to prevent PIH as well as control underlying inflammation that may be present in the skin.
In line with a recent publication20 on the benefits of using HOCl with aesthetic dermatology procedures, we propose that Thoclor HOCl is used as a standard pre- and post-operative application to the wound area to ensure fast complication-free healing.
Chemical peels are a safe and inexpensive way to improve the appearance of the skin. Although the advent of lasers is inevitable, peeling performed with chemical products has a place in the armamentarium of aesthetic and cosmetic medicine.
There are many options available to the physician, from very superficial peels (retinoic acid for example) to the deepest peels represented by phenol peeling. The latter results in intense facial rejuvenation, owing to the action of the phenol employed in the formula which deeply penetrates and permeates the skin. This brings about deep-skin damage followed by a regeneration process with peculiar and long-term characteristics. Nowadays there are new protocols regarding safety and so if used appropriately by the physician, the benefits of a chemical peel will be felt and appreciated by patients. It is an effective method to combat cutaneous ageing.
The recent advancement in the development of pure HOCl, such as that made by Thoclor Labs, has made it possible for the clinician to ensure that the best possible result for a particular skin type is achieved without unnecessary risk.
- Velasco MV, Ribeiro ME, Okubo FR, Bedin V, Steiner D. Facial Skin rejuvenation by chemical peeling: focus on phenol peeling. An Bras Dermatol, Rio de Janeiro, 79 (1): 91-99, jan/fev 2004
- Fitzpatrick TB, Freedberg IM, Eisen AZ et al. Fitzpatrick’s dermatology in general medicine VII, 5th ed. New York: McGraw- Hill, 1999: 1698-703,2702-03, 2937-46
- Draelos ZK. Cosméticos em dermatologia, 2ª ed. Rio de Janeiro: Revinter, 1999: 245
- Juez JL, Gimier LP. Ciencia cosmética: bases fisiológicas y criterios prácticos, Madrid: Consejo General de Colegios Oficiales de Farmaceuticos, 1995: 212
- Draelos ZK. Cosméticos em dermatologia, Porto Alegre: Artes Médicas, 1991:158-59
- Matarrasso SL, Hanke CW, Alsters TS. Cutaneous resurfacing. Dermatol. Clin. 1997;15 (4):569-81
- Coleman III W P, Brody H J. Advances in chemical peeling. Dermatol. Clin. 1997; 15 (1):19-25
- Araújo AL et al. Peeling Químico: avaliação de ácido glicólico, ácido retinóico e ATA. Rev. Cosm. Med. Est. 1995; 3 (3):14-16
- Okano Y et al. Biological effects of glycolic acid on dermal matrix metabolism mediated by dermal fibroblasts and epidermal keratinocytes. Exp Dermatol. 2003;12 Suppl 2:57-63
- Omi T et al. Ultrastructural observations of chemical peeling for skin rejuvenation (ultrastructural changes of the skin due to chemical peeling). J Cosmet Laser Ther. 2010 Feb;12(1):21-4. doi: 10.3109/14764170903376224
- Moy LS, Peace S, Moy RL. Comparison of the effect of various chemical peeling agents in a mini-pig model. Dermatol. Surg. 1996; 22 (5):429
- Tse Y et al. A clinical and histologic evaluation of two medium-depth peels. Glycolic acid versus Jessner’s trichloroacetic acid. Dermatol Surg. 1996 Sep;22(9):781-6
- El-Domyati MM, Attia SK, Saleh FY, Ahmad HM, Gasparro FP, Uitto JJ. Effect of topical tretinoin, chemical peeling and dermabrasion on p53 expression in facial skin. Eur J Dermatol. 2003 Sep-Oct;13(5):433-8.
- Ueda S, Mitsugi K, Ichige K, Yoshida K, Sakuma T, Ninomiya S, Sudou T. New formulation of chemical peeling agent: 30% salicylic acid in polyethylene glycol. Absorption and distribution of 14C-salicylic acid in polyethylene glycol applied topically to skin of hairless mice. J Dermatol Sci. 2002 Apr;28(3):211-8
- The MERCK Index: an encyclopedia of chemicals and drugs, 9th ed. New Jersey: Merck & CO., 1976: 7033
- Glogau RG, Matarasso SL. Chemical Peels. Dermatol. Clin. 1995; 13 (2):263-74
- Stone PA. The use of modified phenol for chemical face peeling. Clin. Plast. Surg. 1998; 25 (1):21-43
- Maloney BP, McCollough EG. Deep-depth chemical peeling. Facial Plast. Surg. 1995; 11 (1):30-38
- Ansel HC, Popovich, NG, Allen LV. Pharmaceutical dosage forms and drug delivery & systems, 6th ed, Baltimore: Williams & Wilkins, 2000: 281-93
- Ashish Bhatia et al. Optimizing Wound Healing for Cosmetic and Medical Dermatologic Procedures. Practical Dermatology March 2018: 42 - 45