The Properties of Skin Peels

By Jacqueline Naeni and Lorna Bowes / 01 Feb 2016

The concept of skin treatments is certainly not new, stories of peeling go back to the time of Cleopatra in Ancient Egypt, while Ayurvedic skincare and medical traditions can be traced back 5,000 years in South Asia and India.


Consumer demand for peels is strong, and there are plenty of choices not only for our patients, but also for us as practitioners. This article will review peeling ingredients that have the dual effect of restoring epidermal components and building the dermis. The possibilities of what can be achieved at different depths of peel will also be explored.

Popularity of skin peels

Since Kim Cattrall’s Samantha Jones had a peel in Sex and the City, there has not only been an increase in awareness, but an increase in demand for skin peels. In May 2014 an article in the Daily Mail2 asked: ‘Could YOU face peeling off a layer of skin to look younger?’ The first four statements in the piece were:

  • Brutal way to beautify is making a comeback
  • Cosmetic chemical face peels are coming back into fashion
  • The skin treatment sees the face covered in a lotion containing acid
  • The acid burns the skin off, which is then peeled off to ‘reveal’ fresh skin

These portrayals of peels and skin rejuvenation do not help consumer understanding of peels, but the demand continues to rise.

Purpose of skin peels

What can actually be achieved by peeling? The main aim of peeling is to visibly improve the structure of the skin. This can be achieved by merely accelerating the natural process of exfoliation, by destroying layers of the epidermis and/or dermis or by protein coagulation or lysis.3 Peels are categorised into three depths of skin penetration, with the vast majority of peels performed falling in to the superficial category – epidermal peeling. Medium depth peels affect the papillary dermis, and there are relatively few deep, reticular dermis peels performed in the UK (Figure 1). Deep peels are, however, gaining in popularity following the European model.

Figure 1: Superficial, medium and deep peeling 

Superficial peels

Most superficial peeling is achieved by topical ingredients or procedures such as microdermabrasion rather than a peel treatment; we have found that peeling caused by topical ingredients can be perceived as sensitivity or flaking skin and good consultation and explanation is needed to generate compliance in early days of using an effective topical exfoliant. To achieve a true epidermal peel requires treatment in-clinic using a range of topical ingredients.

Hydroxy acids

Alpha hydroxy acids (AHAs) have been applied as topical preparations and peeling agents for more than forty years,25 originally being reported at around the same time as vitamin A was first used as a topical preparation for photodamage. Consumers see them as eco-friendly as they are sometimes known as the fruit acids – derived from fruits, nuts and dairy products. According to a study by Beradesca et al, hydroxyl acids increased protection against 5% sodium lauryl sulphate without reducing trans-epidermal water loss (TEWL) by causing a separation of the stratum corneum without compromising barrier function.4 The most commonly used AHA is glycolic acid, many published clinical studies have reported the effects of AHAs in treating photoageing.5 

The main mode of action of AHAs is to damage the desmosomal attachments between corneocytes, and reduce corneocyte cohesion.5 It is not just a peeling effect that occurs however, in their studies, Ditre et al and Okano et al demonstrated a 25% increase in dermal thickness, increase in glycosaminoglycans, enhanced collagen density and improved elastic fibre behaviour.7,8 These effects are unique to hydroxy acids and do not occur with other chemical or mechanical exfoliators that simply work by removing outer epidermal layers.9 

Glycolic acid peels are formulated in strengths up to 70%, to allow for the ideal balance of efficacy versus safety, but it is the pH of the peel that is critical for successful treatment outcomes. This is because penetration, depth and efficacy of the glycolic peel is defined by the pH; many superficial peels are partially neutralised or buffered during manufacture, reducing the sensation of stinging but also reducing efficacy. Glycolic acid peels need to be neutralised to end the penetration and peeling effect, and to allow for greater control of depth and level of peeling for safe and effective clinical results. 

There are many glycolic peels available including Dermaceutic, SkinTech, as well as the myriad of higher pH ‘high street’ glycolic peels Agera, Murad, NeoStrata (the doctors who discovered the desquamating effects of glycolic acid are the founders of NeoStrata Company) and many other cosmetic and cosmeceutical brands. The AHA lactic acid is sometimes used for chemical peels such as gloTherapeutics lactic 15%, although peel preparations are available up to 50%. Lactic acid is known to be naturally hydrating because the lactic acid converts to lactate, which is a component of natural moisturising factor, hence it is generally considered to be gentler than other AHAs such as the more portent mandelic and glycolic acids.10

Resorcinol
Resorcinol is a derivative of phenol and has been used in treatments for peeling for almost 150 years.12 Resorcinol works by disrupting the hydrogen bonds in keratin, so it is primarily used for addressing pigmention.13 Currently, Resorcinol is most commonly used in combination peels such as Jessner’s peels due to the side effect profile. Resorcinol has been associated with side effects such as myxedema, thyroid dysfunction and cardiac arrythmia;14 therefore, it is highly recommended that allergy testing is performed before using resorcinol as a peeling agent.15

Retinoic acid
Vitamin A is widely used in topical formulations that vary from mild derivatives to prescription-only high strength formulations. There are three main forms and many manufacturer specific sub-forms:

1. Retinol (vitamin A)
2. Retinal (retinal aldehyde not to confuse with retinal which refers to the retina)
3. Retinoic acid (vitamin A acid or vitamin A1, tretinoin)

Topical retinoids are frequently used to treat photo damage and acne.3 Retinoic acid is the bioavailable form of vitamin A, retinol is converted to retinoic acid in the dermis. Studies have reviewed the safety and efficacy of vitamin A peels, with one study showing that a 1% tretinoin peel, applied for six to eight hours performed on 15 women aged 23-40 years with Fitzpatrick Types I to IV, achieved the same result at two and a half weeks as topical tretinoin for a period of four to six months.16 Vitamin A peels may enhance the effects of other peel types; for example, salicylic and glycolic acid peels enhance desquamation.16

Jessner’s solution
Jessner’s solution and modified Jessner’s are well-known exfoliators and reports of their uses have been seen for more than a century.26 Originally, Jessner’s was a combination of resorcinol 14%, salicylic acid 14% and lactic acid 14%. Modified Jessner’s contain various combinations, typically salicylic acid 17%, lactic acid 17% and citric acid 8%.17 Jessner’s has been used in combination with AHA and TCA peels, as a thorough skin preparation due to it’s keratolytic properties.18

Beta hydroxy acids
Salicylic acid is the most frequently-cited beta hydroxyl acid (BHA). It is lipophilic, whereas AHAs are water-soluble, which is why salicylic acid is often chosen for oily and acne prone skins. Salicylic acid is able to penetrate hair follicles and sebaceous glands and exhibits comedolytic properties.11 Manufacturers who use salicylic acid include Epionce, Mene & Moy, Cosmedix, Medik8, NeoStrata, ZO, Priori and Jan Marini. The application of salicylic acid as a peel solution generates a frost on the skin, which is a precipitate and should not be confused with epidermolysis or precipitated dermal protein.

Combinations
Many manufacturers now combine ingredients either in protocols or in peels, which are all designed to suit different patients.

Common hydroxy acid combinations include:

  • Skin Tech Easy Phytic Peels: glycolic, lactic, phytic and mandelic acid
  • Skin Tech Easy Droxy Versicolour: glycolic, lactic, salicylic, citric and kojic acids
  • ZO 3Step Stimulation Peel: glycolic, salicylic, and lactic acid
  • SkinCeuticals protocols: glycolic, salicylic acid and resorcinol
  • Agera: salicylic, l-ascorbic and lactic acid
  • NeoStrata: protocols combining glycolic acid with mandelic acid or citric acid and a home daily peel with glycolic acid and N-acetyl Tyrosinamide

Medium peels

Also known as trichloroethanoic acid and trichloromethane carboxylic acid, trichloroacetic acid (TCA) first became topical in the 1880s12 and returned to popularity in the 1960s.19 TCA is now widely used in the aesthetic industry, both as a single ingredient peel and in combinations. Unfortunately, TCA is neither homogenous nor stable, and when made up as a simple aqueous solution, the concentration will not be uniform, which will lead to uneven results and adverse events.3 However, manufactures have developed stable adjuvant formulas for ease of use and optimal results.

Low strength TCA peels (<20%) have been shown to reduce fine lines and wrinkles, but not deep wrinkles and scars, whereas higher strength TCA up to 40% induces dermal necrosis.3,6 However, post-inflammatory hyperpigmentation and scarring are known documented side effects. Therefore, particular care is needed when addressing the needs of Fitzpatrick Skin Types IV to VI.6 TCA causes protein to denature leading to keratocoagulation and keratinocyte death, this presents as a white frost. As the skin re-epithelialises, collagenesis is observed and abnormal keratinocytes are replaced by healthy cells.20,21 TCA can also be supplied by a pharmacist using a weight in volume (W/V) dilution i.e. 15%. TCA is made by adding sufficient water to 15g TCA to make a 100ml solution. TCA peels that are available include Skin Tech Only Touch, Easy TCA and UniDeep; Obagi Blue Peel and ZO Controlled Depth Peel. TCA in peel combinations are available from manufacturers such as gloTherapeutics AlphaBeta, Triplex (TCA with glycolic and salicylic acids); PCASkin Ultra Peel Forte TCA with lactic, azelaic and kojic acids.

Deep peels

Phenol and combination peels which include phenol, have been described over the past 200 years, with phenol originally being used as a disinfectant and, from the early 20th Century, as an anaesthetic.22 In the 1940s and 1950s, use of phenol peels created a backlash and rejection by medical professionals.23 Recently, work by Deprez in Spain, Vigneron in France and Figureido in Portugal, among others, has reinvigorated use.3 Phenol dissolves the epidermal layers in the first 36 hours after application, the basal layer is restructured and melanin synthesis is reduced.3 In the papillary dermis, the elastotic layer is destroyed and new collagen fibres appear in the Grenz zone, and an effective network of elastic fibres have been demonstrated.24

After the application of a phenol peel, it takes approximately six weeks for normal skin to regenerate. The area will remain red for several weeks, or sometimes even months. Reassurance is needed for patients to tolerate this, and the fact that new blood vessels are developing helps to alleviate some of the concerns post deep peel. Histological changes have been reported 15 years after a phenol peel, so one phenol peel is sufficient in most cases for long-lasting rejuvenation.3 An example of a target phenol peel is Skin Tech Lip and Eyelid Formula and there are others that make their own blend.27

Deep Peel Combinations
Many clinics combine peels with other modalities such as medical microneedling, microdermabrasion, laser resurfacing, dermal fillers and boosters, mesotherapy and chemical denervation. Common deep peel combinations include:

  • Perfect Peel: glutathione, kojic acid, TCA, retinoic acid, salicylic acid, phenol
  • Vitality Institute VI Peel: TCA, tretinoic acid, salicylic acid and phenol
  • Skin Tech Easy Phen Light: TCA and phenol

Conclusion

This brings us to the question: which peel do you choose for your patients and why? These days we have so much choice of peel products to offer, so which do we choose? In the experience of the authors, we have found that the consultation process is so important to help decide which peel to use. There are many important factors that need discussing with the patient such as:

  • What is the patient’s key skin concern and expectation of the treatment?
  • Is the patient medically suitable for a peel?
  • Which Fitzpatrick skin type are they?
  • Have they had peels in the past, and if so, were they happy?
  • Will the patient comply with the pre and post-peel skincare advice?

It’s very important to discuss the expected results of the treatment, as each patient is different and the outcome will vary from person to person. We need to find out during our consultation process what the patient’s lifestyle/work commitments are like. Does the patient want a peel where they can return to work immediately or the following day, or a peel that may result in them needing more time off work because of the extra downtime? All of these factors need to be discussed during the consultation and the answers will therefore help in the decision process. 

Financial implications need to be discussed before any treatment plan can begin as prices vary from peel to peel. If the patient’s expectations outweigh what they may be able to afford, we need to highlight this before starting any treatment that may not be the most appropriate for them. We must offer our patients choice in our clinics by combining peels with professional skincare and other modalities such as medical microneedling, microdermabrasion, laser resurfacing, dermal fillers and boosters, mesotherapy and chemical denervation. Only the best combinations will help enhance patients’ results.

Disclosure: Lorna Bowes is the director of AestheticSource, the distributor of NeoStrata and SkinTech products. Jacqueline Naeni is a trainer for AestheticSource.

References

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  8. Okano Y, Abe Y & Masaki H, et al., ‘Biological effects of glycolic acid on dermal matrix metabolism mediated by dermal fibroblasts and epidermal keratinocytes,’ Exp Dermatol 12(2003), pp.57-63.
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