Chemical Peels 

Updated: Jul 26, 2017
Author: Gabriella Fabbrocini, MBBS, MD; Chief Editor: Dirk M Elston, MD 

Overview

Background

Chemical peeling, also termed chemexfoliation, represents accelerated exfoliation or skin damage induced by caustic agents that cause controlled damage, followed by the release of cytokines and inflammatory mediators, resulting in thickening of the epidermis, deposition of collagen, reorganization of structural elements, and increases in dermal volume. This process decreases solar elastosis and replaces and reorients the new dermal connective tissue. The result is an improved clinical appearance of the skin, with fewer rhytides and decreased pigmentary dyschromia, and a more youthful appearance.

The images below depict a patient during and after a salicylic acid peel.

Men also request chemical peeling. This 56-year-ol Men also request chemical peeling. This 56-year-old man is in the process of a salicylic acid peel.
Same patient as shown above following a successful Same patient as shown above following a successful chemical peeling.

In recent years, a large shift has occurred in the manner and depth to which peels are performed. Lasers largely have supplanted deep chemical peeling because of the control of depth they afford, their lesser effect on pigmentation, and their ease of use, with no chemical adverse effects. Superficial peels, in contrast, have increased in popularity. Various agents are used; for simple exfoliation, glycolic or lactic acids are now commonly found in almost all moisturizers and in many makeup bases.

Aging skin undergoes a number of changes. With time, it thins, falls, and creases along muscular and gravitational folds. Compared with the effects of simple aging on skin, sun damage leads to additional and different problems, including thickening, solar elastosis, and resultant pigmentary irregularities. Carcinogenic effects lead to actinic keratoses, basal and squamous cell cancers, and, less directly, to melanomas.

Scarring from trauma or acne contributes to an irregular skin surface. True skin laxity in the form of brow ptosis, eyelid bags, jowls and loss of neckline, ear lobule elongation, nasal tip drop, upper lip thinning, and other manifestations are currently treated surgically with facial rejuvenation procedures (eg, face lift, brow lift, rhinoplasty, lip augmentation). Conversely, these procedures do not help skin textural damage. Fine lines, pigmentary irregularities over a broad area, and aging skin are treated with peeling using either chemical or mechanical means.

A discussion of mechanical peeling is warranted for thoroughness. Lasers largely are used for skin ablation, with the carbon dioxide ultrapulsed laser currently used most often. The Er:YAG laser is used more for superficial resurfacing when little tightening and superficial depth of peel are required.[1] Fractional laser resurfacing devices have shown encouraging results, especially for acne scarring.[2] Many surgeons still use dermabrasion. The lack of control and lack of ability to resurface evenly have resulted in the supplantation of this technique by those already discussed. Microdermabrasion is currently a popular technique because no downtime or discomfort is associated with the procedure. Medical devices tend to have stronger suction, and more abrasive crystals are used, while spa and lay devices tend to be gentler, with less overall effect but increased safety. In general, mechanical abrasion tends to improve scarring more than chemical peeling agents, given similar depth of penetration.[3]

Currently, a number of categories of chemical peeling agents available for rejuvenating the skin can be found. These range from superficial formulations available over the counter to deep chemical agents that should only be applied by a physician in a controlled setting. When used in the proper setting with appropriate technique, nearly all of these products have proven successful in improving quality and appearance of facial skin.

The goal of chemical peeling is to remove a predictable uniform thickness of damaged skin. Normal wound healing and skin rejuvenation follow, while complications such as scarring and pigmentary changes are minimized.

Indications

The indications for a chemical peel, since it is largely a cosmetic procedure, depend on the patient's tolerances and wishes for correcting skin textural problems. Many individuals do not wish to improve skin texture despite severe problems, and others desire marked improvement in relatively minor problem areas. Treatments vary with the severity of the condition and the wishes of the patient. These wishes should be tempered with information on what is possible and what is desirable for the patient in terms of treatment. Approach each patient truthfully, discussing possibilities, risks, benefits, and alternatives.

Indications related to pigmentary disorders are as follows:

  • Melasma

  • Postinflammatory hyperpigmentation

  • Freckles

  • Lentigines

  • Facial melanoses

  • Periorbital hyperpigmentation

Indications related to acne are as follows[4, 5] :

  • Superficial acne scars

  • Postacne pigmentation

  • Comedonal acne[6]

  • Acne excoriée

  • Acne vulgaris - Mild to moderately severe acne

Indications for aesthetic concerns are as follows[4, 7] :

  • Photoaging

  • Fine superficial wrinkling

  • Dilated pores

  • Superficial scars

Indications related to epidermal growths are as follows:

  • Seborrheic keratoses

  • Actinic keratoses

  • Warts

  • Milia

  • Sebaceous hyperplasia

  • Dermatosis papulosa nigra

Upper epidermal defects, such as melasma, can be treated with superficial peels, while deeper defects, such as deep wrinkles, may require a deep peeling agent.[8] Medium-depth (superficial dermis) defects, such as mild dermatoheliosis, require a medium-depth peel. Deep perioral rhytides may require a deep peel, such as the Baker-Gordon solution.

Aging faces are common to all and recognized as such. Distinguish between textural skin damage treatable by resurfacing or skin rejuvenation and actual ptosis or falling of major structures treatable by surgical interventions.

Contraindications

Relative contraindications are determined by the skin type of the patient and the defect being treated. To optimize the procedure, some classifications are very useful, such as the Fitzpatrick and the Glogau photoaging classifications. See Procedure Planning for detailed information on Fitzpatrick and the Glogau photoaging classifications.

Absolute contraindications include the following:

  • Active bacterial, viral, fungal, or herpetic infection
  • Open wounds
  • History of drugs with photosensitizing potential
  • Preexisting inflammatory dermatoses (eg, psoriasis, atopic dermatitis, pemphigus)
  • Facial cancers, especially facial melanoma
  • Uncooperative patient (patient is careless about sun exposure or application of medicine)
  • Patient with unrealistic expectations
  • For medium-depth and deep peels, history of abnormal scarring, keloids, atrophic skin, or isotretinoin use in the last 12 months

Other considerations

Degree of photoaging damage

Patients with either severely damaged skin or excellent skin may not be good candidates for chemical peels. Sun-damaged skin shows epidermal changes, elastosis, and collagen distortion in the midreticular dermis.

To eradicate photodamage, deep peels are required. More superficial peels, even when performed in repetitive fashion, do not reach the affected histological level and therefore have a minimal effect on photodamaged skin.

Smoking

Patients must understand the necessity for smoking cessation.

The dynamic action of puffing can worsen perioral rhytides, and the chemicals in the smoke can cause enzymatic reactions that weaken the skin and cause further wrinkling around the mouth and eyes.

Prior cosmetic surgery

Waiting several months following surgery that involves the face is recommended. Give the skin time to heal prior to subjecting it to chemexfoliation.

Compliance with prepeel and postpeel treatment must be assured. The patient must be motivated enough to adhere to a daily regimen for a few weeks before and after the procedure.

General health

With phenol peels, the patient should be in good general health because phenols can cause arrhythmias. Phenol is directly toxic to myocardium. Cardiac arrhythmias have been recorded in up to 23% of patients when a full-face peel was performed in less than 30 minutes. These arrhythmias have included tachycardia, premature ventricular beats, bigeminy, atrial tachycardia, and ventricular tachycardia. Adequate patient management reduces this complication rate to less than 7%.

Good kidney and liver function are necessary for adequate excretion and detoxification. A screening blood chemistry that includes blood urea nitrogen, creatinine, and liver function is wise. ECG monitoring is necessary during the peeling process. No hepatorenal or central nervous system toxicities have been reported in the literature with properly performed chemical peels.

Mental health

Patients who are mentally unstable may be overly self-conscious and may not be prepared for their aesthetic appearance immediately following the peel.

Medications

A thorough medical and drug history is very important.

Medical conditions such as cardiac, hepatic, or renal disease may influence treatment decisions and the choice of peeling agents.

Exogenous estrogens, oral contraceptives, and other medications may be photosensitizing and predispose patients to pigmentation complications after chemical peeling and worsening the skin discoloration that the chemical peel was intended to eradicate.

Patients taking blood thinners, such as warfarin, should avoid deep peels because of the possibility of blood oozing from the peel site. Patients taking aspirin usually do not have complications, but, if the medication is not necessary, advise them to stop taking it 1 week prior to a deep peel.

Herpes

A history of herpes simplex requires antiviral prophylaxis from the immediate prepeel period until reepithelialization is complete. Acyclovir (400 mg) should be started 2 days prior to the peel and continued for 5 days after the peel to reduce the risk of recurrent herpes infection.

Some dermatologists advise prophylaxis in all patients to avoid the risks of a herpetic outbreak.

Any existing lesion must heal completely before undergoing a chemical peel.

History of scarring

Patients need to be asked if they have a history of hypertrophic scarring. Many people who have hypertrophic scarring can develop keloids. This usually is found in patients with Fitzpatrick skin types 5 and 6 but can develop in patients with skin types 1, 2, 3, and 4.

Medium and deep peels penetrate into the superficial and deep dermis, which may stimulate keloidal development in patients who are inclined to develop keloids. Weak superficial peels can be considered in patients with skin types 4 and 5 because the penetration is only into the epidermis. Patients with a history of scarring are not candidates for major skin resurfacing, such as laser or medium/deep peels.

Expectations

A discussion between the physician and patient is necessary prior to a chemical peel, especially a deep peel.

Examples of before-and-after results should be shown, and the possibility of complications must be explained to the patient.

Follicle unit density

Previous use of isotretinoin must be noted. Patients should wait until 6 months after the last dose of isotretinoin to reduce the risk of scarring.

Patients who have had recent radiation treatment need to have a skin biopsy performed to ascertain the existence of hair follicle units, because these follicle units are where the reepithelialization occurs.

Technical Considerations

Peeling agent concentration

When combination peels are used, better clinical results can be achieved with reduced risk of complications.[9] Peeling agent concentration can vary, even though the label indicates the same concentration. The different methods used to determine the concentration of an acid can produce some variation.

The most frequently used peeling agents are salicylic acid, glycolic acid, pyruvic acid, lactic acid, mandelic acid, Jessner solution, trichloroacetic acid, and phenol.

From strongest to weakest, these methods are dilutions of a saturated solution, the weight-to-weight method, the weight-to-volume method, and grams of acid crystal mixed to 100 mL of water.

Free acid availability

Molecules found in chemical peels are either alcohols that contain a carboxyl (-COOH) and hydroxyl (-OH) groups or regular acids. It has been suggested that according to their chemical properties, substances used in chemical peels are classified as metabolic, caustic, or toxic.

The pH of the agent, or free acid available (pKa), is another measurement. The pKa of the solution is the pH at which half is in acid form; therefore, a lower pKa means that more free acid is available. Many products advertise the acid percentage; however, pKa is a more accurate determinant of strength.

Outcomes

The outcome generally is excellent once patient expectations are adjusted to the procedure. The patient must know what to expect from the surgery and during the healing process. Giving the patient realistic expectations for each stage of healing is imperative to the success of the entire procedure.

After a deep peel, the skin is new and supple. Some of the rhytides return as the swelling resolves. Approximately 1 month after the peel, the skin appears wrinkled. After it begins to thicken, many of these rhytides resolve over the ensuing months. A repeat peel can be performed after 1 year if necessary. Superficial peels can be repeated every few weeks if needed. Many superficial peels do not produce the same effects as a deep peel. The skin continues to weather and age after the procedure, but the effects of the peel are permanent.

A noted decrease in the incidence of superficial skin cancers and actinic keratoses occurs after resurfacing procedures.

Etiology of Facial Aging

The etiology of facial aging is a broad subject. This article briefly discusses aging and contrasts it with sun and environmental damage. 

When not compounded by extraneous factors, skin aging basically is the process of atrophy. Loss of subcutaneous tissue is the most obvious and recognizable sign of aging; however, skin, skin appendages, and cutaneous blood supply also atrophy with age. Both the epidermis and dermis thin, and cutaneous strength and elasticity are lost. Dermoepidermal adherence afforded by rete pegs is lost, and blistering or superficial epidermal loss commonly occurs with aged skin. Overall thinning and loss of integrity and wall strength of the cutaneous vasculature cause easy bruising.

Atrophy of the skin is a well-known process that occurs with aging. This process typically begins during the fourth decade of life. The outermost portion of the epidermis, the stratum corneum, becomes disorganized and less effective as a protective barrier to the external environment. A gradual decline in the number of melanocytes populating the basal layer of the epidermis also occurs. The dermoepidermal junction becomes flattened because of a decrease in the number of dermoepidermal papillae. More significant changes can be seen within the dermis, where an overall loss of organization occurs as this layer begins to thin with age. The amount of ground substance decreases, and elastic fibers degenerate, making the skin less resistant to deformational forces. Collagen is also lost, and the relative proportion of type I to type III collagen is reduced.

Environmental damage to skin often is explained incorrectly in the literature because of confusion between the short- and long-term changes that occur. Initially, as with most damage to the human body, the response is inflammatory. This tends to subside rather quickly in the skin, but continuous damage can result in prolonged inflammatory responses. Although postinflammatory hyperpigmentation is often considered a limited medical condition, most individuals express it to some extent, and prolonged exposure to damaging environmental factors results in tanning and prolonged hyperpigmentation. The increased volume of skin from inflammation tends to be transient and is caused by increased water volume from increased proteoglycans and glycosaminoglycans.

The true long-term damage to skin from environmental stresses is a decrease in the water volume and an increase in damaged cutaneous proteins. In particular, the elastic fibers tend to form tangled masses of nonelastic elastin remnants. This leads to increased volume of skin without functional elements. The solar elastosis or heliosis that is observed histologically is the end stage of this damage. In much the same manner that scarring or fibrosis is observed as the end stage of renal or hepatic disease, scarring and remnants of proteinaceous elements tend to be the end stage of cutaneous disease. Although contracture is present, the general trend in environmental damage of the skin is toward increased thickness, especially of the dermis. This thickening is with nonelastic and structurally weak skin. Sun damage, especially from ultraviolet (UV)–A wavelengths, causes ionization and oxidation of dermal elements and genetic information, resulting in premalignant and malignant skin lesions.

Many years of acne (both cystic and rosacea) increase the blood flow to skin and tend to hypertrophy the basic elements. Scar tissue also deposits and can contract, leading to uneven skin surfaces. True cysts and sinus tracts commonly result, and ice pick lesions usually are the visible manifestations of these processes. Actinic keratoses and lentigines are two examples of actinic damage, or photodamage.[10]

Skin Anatomy

Before embarking on chemical peeling, one must have a thorough knowledge of skin anatomy and normal wound healing. The skin serves as a protective barrier, preventing exposure of internal tissues to trauma, UV radiation, temperature extremes, toxins, and bacteria. Other important functions include sensory perception, immunologic surveillance, thermoregulation, and control of insensible fluid loss.

The skin is composed of two mutually dependent layers, the epidermis and dermis, which rest on a fatty subcutaneous soft tissue. The epidermis contains no blood vessels and is dependent entirely on the underlying dermis for nutrient delivery and waste disposal. This occurs by diffusion through the so-called dermoepidermal junction. The primary function of the dermis is to sustain and support the epidermis.

Epidermal appendages are intradermal epithelial structures lined with epithelial cells that have the potential for division and differentiation. These structures are named from the fact that they develop as down-growths or diverticula of the epidermis into the dermis. These appendages serve an important role as a source of epithelial cells, which are responsible for re-epithelialization when the overlying epidermis is removed or destroyed.

Epidermal appendages include sebaceous glands, sweat glands, apocrine glands, mammary glands, and hair follicles. Sebaceous glands are highest in concentration on the face and scalp, where as many as 900 glands/cm2 may be found. Epithelial appendages are located deep within the dermis. In the face, these appendages may also be located in the subcutaneous fat beneath the dermis. The deep location of these structures and their density in the face account for the remarkable ability of this area to re-epithelialize the deepest cutaneous wounds.

Mechanism of Action in Chemical Peeling

Chemical peeling is the process of applying chemicals to the skin to destroy the outer damaged layers. It causes controlled destruction of a part of or the entire epidermis, with or without the dermis, leading to exfoliation and removal of superficial lesions, followed by regeneration of new epidermal and dermal tissues.[9] The epidermis regenerates from the epidermal appendages located in the remaining dermis. This process begins within 24 hours of wounding and is usually complete in 5-10 days. The new epidermis shows greater organization and vertical polarity, with the disappearance of actinic keratoses and lentigines. Dermal regeneration is a slower process but is usually complete within several months. The regenerated dermis demonstrates less elastosis and improved organization, with compact horizontally arranged bundles of collagen interspersed with elastic fibers. Ground substance is decreased and telangiectasias are absent. The overall result is soft supple skin that appears more youthful with fewer rhytides and dyschromias.

Different agents and formulations are chosen based on their depth of penetration and risk profile. Destruction confined to the epidermis results in rapid healing without scarring, although some pigmentation change may be present if melanocytes are damaged. This superficial wounding has the disadvantage of producing less dramatic results but is very safe. Deeper wounding, extending into the papillary and, sometimes, reticular dermis, produces more dramatic results. However, deeper penetration eradicates a portion of the epidermal appendages, making healing slower and scarring more likely. Penetration into the reticular dermis entails a very high risk of scarring.

The weaker agents (eg, alpha-hydroxy acids) change the pH sufficiently to cause a superficial shock to the cells and, depending on many variables, cell injury or death. When used with a moisturizer, the acid acts simply to cause cellular and intercellular swelling and plumping, leading to a transient increase in cell and matrix size and lessening of fine lines and rhytides. Sequential treatments lead to exfoliation and a smoother complexion. Continued irritation can lead to many of the same effects of tretinoin or retinoid treatment (ie, increased thickness of dermis, increased blood flow to skin).

Stronger agents such as phenol (with various additives such as croton oil and glycerin) and trichloroacetic acid (TCA) produce a chemical necrosis of the skin to variable depths, depending on numerous controlled and uncontrolled variables.

Other factors that can affect the depth of peel include the following:

  • Presence of skin surface oils and dirt

  • Skin water content

  • Temperature of the room, skin, and solution

  • Humidity of the air

  • Length of time the solution is left in contact with the skin

  • Occlusion or nonocclusion

  • Batch of croton oil

  • Thickness of epidermis and dermis

  • Presence of hyperkeratotic lesions

 

Periprocedural Care

Patient Education and Consent

Patient instructions

Following the peel, the patient must follow the instructions given by the physician to prevent complications. If possible, the patient should stay out of the sun; when unavoidable, the patient should apply a strong sunscreen and wear a hat. An ointment, such as petroleum jelly or bacitracin, should be applied to the involved skin.

The patient should be made aware that the skin will exfoliate and may look cosmetically unattractive for a period depending on the depth of the peel. For superficial peels, a follow-up appointment can be scheduled at the time of the next peel. For deeper peels, patients should be seen 2-3 times the week following the peel to provide for early intervention if problems develop.

The patient should be instructed to remain vigilant for signs of infection. If the patient has a history of cold sores, treating the patient with acyclovir (400 mg PO bid) or an equivalent drug is advisable, beginning 2 days prior to the peel and continuing for 7 days after the peel.

Elements of informed consent

The patient must be educated concerning the chemical peel process and signed consent is advised if performing a medium or deep peel. The patient has to be questioned about his or her general health status, medications (eg, oral isotretinoin), smoking, previous cosmetic procedures (eg, surgical lifts, fluid silicone injections), recurrent herpetic outbreaks, and keloid formation.

A detailed consent form listing details about the procedure and possible complications should be signed by the patient. The consent form should specifically state the limitations of the procedure and should clearly mention if more procedures are needed for proper results. The patient should be provided with adequate opportunity to seek information through brochures, presentations, and personal discussions. The need for postoperative medical therapy should be emphasized.

Preprocedural Planning

Although the technique of chemical peeling is relatively simple, the challenge lies in proper patient and peeling agent selection. In general, the more severe the actinic damage or advanced the aging changes, the more aggressive the treatment should be. Once the patient is appropriately selected to undergo a chemical peel, informed consent, including a thorough discussion of possible complications, is obtained.

Adequate evaluation and photographic documentation of the patient prior to peeling is essential. This includes consideration of the severity of actinic damage, depth and number of rhytides, and need for additional or alternative procedures. The patient with deep rhytides and excessive facial skin laxity is likely to respond better to traditional rhytidectomy. The patient with moderate-to-severe photodamage and medium-to-fine rhytides may be a more optimal candidate for chemical peeling.

Some patients may benefit from both procedures because rhytidectomy addresses skin quantity, whereas peeling addresses skin quality. However, these procedures cannot be recommended as concurrent interventions. In general, for safety purposes, a minimum of 3 months is recommended between the procedures to allow for adequate wound healing.

Fitzpatrick and the Glogau photoaging classifications

A cornerstone of the evaluation of the patient for chemical peeling is the Fitzpatrick and the Glogau photoaging classifications of sun-reactive skin types and a visual grading system used to quantify photodamage.

Fitzpatrick skin typing is graded from 1-6, with the first 3 skin types being white skin with progressively more active responses to tanning. Type 4 is light-brown skin, and type 5 is dark-brown skin. Type 6 skin never tans and is essentially black skin with an equivalent sun protective factor (SPF) of 8. Fitzpatrick skin types 5 and 6 are usually not ideal candidates for medium and deep peels. The best candidates are the light skin types, 1, 2, and 3, which are at less risk of complications such as pigment dyschromia and scarring. Although skin types 5 and 6 are not ideal for peels, they can be peeled using superficial agents such as salicylic acid or glycolic acid.

The Glogau photoaging classification is a visual grading system used to quantify photodamage. Patients with photoaging type I are not good candidates for deep peeling because the peel may be more damaging than beneficial, while a superficial peel would be more efficacious. Patients with type IV photodamage may benefit from deep peeling, while a superficial peel may not make much of a difference. Patients with skin types II and III ordinarily benefit from superficial or medium-depth peels, depending on the exact circumstances of the patient. Other variables also should be considered, including the Fitzpatrick skin type, when determining which peeling agent to use.

In type I, the patient, usually is in the second or third decade of life, shows mild early photoaging that consists of mild pigmentary changes, does not have keratoses, and has minimal wrinkles. The patient requires minimal or no makeup.

In type II, the patient has wrinkles that appear when he or she makes facial gestures or other dynamic facial muscle activity (ie, "wrinkles in motion"). Early-to-moderate photoaging is recognized by early senile lentigines, keratoses that are palpable but not visible, and the emergence of parallel smile lines. The patient is usually in the third or fourth decade of life. Female patients usually wear some foundation.

In type III, the patient has wrinkles not dependent on facial movement (ie, "wrinkles at rest"). Advanced photoaging is recognized by obvious dyschromia, telangiectasias, visible keratoses, and wrinkles at rest. The patient is usually aged 50 years or older, and female patients almost always wear heavy foundation.

In type IV, the patient has only wrinkles, and nearly no smooth skin. Severe photoaging is characterized by yellow-gray coloration of the skin, prior history of skin malignancies, and skin that is thoroughly wrinkled. The patient is usually in the sixth or seventh decade of life. In addition, the patient cannot wear makeup because it cakes and cracks in the wrinkles.

Medical and drug history

A thorough medical history and review of systems should be completed in concert with the physical examination. Preexisting cardiac, hepatic, and renal disease may influence the treatment decision and choice of peeling agents. History is taken to determine the amount of sun-induced damage, history of hypertrophic scarring or keloid formation. Other items of interest include a history of prior surgeries, dermabrasion, or recent laser therapy.

The use of exogenous estrogens, oral contraceptives, and other photosensitizing medications are known to predispose to unpredictable pigment changes. Therefore, such agents should be avoided several weeks before and after a peel. Medicines such as isotretinoin need to have been stopped for at least 12 months prior to chemical peeling.

If the patient has a history of herpes simplex infection, the physician should provide antiviral prophylaxis several days before and after the peel. This helps minimize chances of unwanted viral reactivation as the re-epithelialization process occurs. Some authors, in fact, advocate prophylaxis in all patients. Toward this end, it is also advisable to allow any existing lesion to heal completely before proceeding with a chemical peel.

Patient selection and compliance

The ideal candidate has minimal sag or severe skin excess but many fine lines and rhytides. Patients with fair complexions are better suited to peels primarily because of possible postinflammatory hyperpigmentation in other skin colors. These long-term concerns can largely be circumvented with proper pretreatment and posttreatment using bleaching agents. The hypopigmentation commonly observed after deep chemical and laser peels generally occurs in whites and can be avoided with a more superficial peel or by peeling adjacent areas lightly to blend the areas. If a deep peel is necessary, discussing the likely probability of hypopigmentation with the patient is best to ensure that when it occurs it is an acceptable result.

Patients must also be aware that cooperation and compliance with the postpeel regimen is required to ensure normal wound healing and to avoid complications. Patients likely to be noncompliant or unable to avoid sun exposure because of occupation are unsuitable candidates. In general, men are considered less optimal candidates because of thicker, oilier skin that risks uneven penetration of the peeling agent. Men are also less likely to be willing to use camouflage makeup in the event of pigmentary disturbances. Patients with a decreased number of epithelial appendages from prior radiation treatment or current isotretinoin (Accutane) use are also poor candidates because healing will proceed more slowly and scarring is more likely.

Equipment

Various chemical peeling agents are used for superficial, medium-depth, or deep peels.

Trichloroacetic acid

Trichloroacetic acid (TCA) can be used to create a superficial, medium, or deep peel. Apart from variables such as patient skin type, adequacy of skin priming, layers of acid applied, and technique of application, the most important factor affecting the depth of the peel is the concentration of TCA used. Concentrations of 10-25% are used for intraepidermal peels, whereas 30-40% concentrations are used for papillary dermal peeling. TCA is most commonly used for medium-depth peels, especially to treat pigmentation disorders and early facial rhytides. A combination of TCA 3.75% and lactic acid 15% can be used in patients with periorbital hyperpigmentation. Patients with skin types II, III, or IV can be successfully treated with this chemical peeling every week for a series of 4 treatments.

TCA (10-35%) has been used for many years and is safe to use at lower concentrations. At higher concentrations, such as 50% and greater, TCA has a tendency to scar and is less manageable than other agents used for superficial peels. TCA is found in several proprietary peels at varying concentrations, and some kits have instructions and buffering agents so the peel can be diluted as deemed necessary. The endpoint is frosting for TCA peels, which are neutralized with either a neutralizing agent or cold water, starting from the eyelids and then proceeding to the entire face.

Jessner solution

Jessner peel solution is a combination of salicylic acid 14%, lactic acid 14%, and resorcinol 14% in alcohol. This agent is easy to use, with no timing necessary. Apply the agent, wait for a light frost, and then neutralize with water. The solution is applied to the skin with a soft applicator in patients with thin, sensitive skin or is rubbed in with gauze squares in patients with thick sebaceous skin.

The depth of the peel depends on the number of coats of solution applied. A very superficial Jessner peel results in faint erythema, which may be associated with a light powdery-looking whitening of the skin surface.

Salicylic acid

Salicylic acid has been used for several decades and is found in medications such as Whitfield's ointment at 4% and Trans-Ver-Sal at 17% concentrations. Adverse effects, usually only found with high-dose oral ingestion, include headache, nausea, and ringing of the ears, each of which may be resolved with a few glasses of water and rest. These have never been reported with a peel procedure. For salicylic acid peels, the endpoint is the pseudofrost formed when the salicylic acid crystalizes. This type of agent is very safe, and patients generally tolerate the procedure well.

Salicylic acid is lipid soluble; therefore, it is a good peeling agent for comedonal acne. The salicylic acid is able to penetrate the comedones better than other acids. The anti-inflammatory and anesthetic effects of the salicylate result in a decrease in the amount of erythema and discomfort that generally is associated with chemical peels. The most common concentration used is 20-30% and can be purchased in easy-to-use kits.

Beta-lipohydroxy acid

A newly introduced agent, beta-lipohydroxy acid, is a salicylic acid derivative and has properties that could possibly expand the clinical use of peels.[11, 12]

Carbon dioxide

Carbon dioxide peels use a solid block of carbon dioxide ice dipped in an acetone-alcohol mixture, which is then applied to the skin for 5-15 seconds, depending upon the desired depth.

Carbon dioxide is easier to use, and the depth of the peel can be controlled more easily than with liquid nitrogen; carbon dioxide is at -78°C, while liquid nitrogen is at -196°C.

Alpha-hydroxy acid

Alpha-hydroxy acid peels include lactic acid, glycolic acid, tartaric acid, and malic acid that are synthesized chemically for use in peels. Various concentrations can be purchased, with 10-70% concentration used for facial peels, most commonly 50% or 70%.

Alpha-hydroxy acids are weak acids that induce their rejuvenation activity by either metabolic or caustic effect. At low concentration (<30%), they reduce sulfate and phosphate groups from the surface of corneocytes. By decreasing corneocyte cohesion, they induce exfoliation of the epidermis. At higher concentration, their effect is mainly destructive. Because of the low acidity of alpha-hydroxy acids, they do not induce enough coagulation of the skin proteins and therefore cannot neutralize themselves and must be neutralized using water or a weak buffer.

Pyruvic acid

Pyruvic acid is used in superficial peeling and if difficulty is encountered controlling peel depth. A product currently is being developed that uses ethyl pyruvate and has a higher pH and greater buffering ability than other related products.

Combination peels

Three combination peels currently being used are carbon dioxide and TCA 35%, Jessner solution and TCA 35%, and glycolic and TCA 35%. These peels are as effective as the other medium-depth peels, with less chance of scarring and pigment dyschromia. An endless number of combinations are possible, more than can be covered in this overview.

TCA 50% is seldom used because of a higher risk of scarring and the availability of the combination peels.

Full-strength phenol (88%) is a very caustic agent that causes immediate keratin agglutination, preventing further penetration of the agent deeper into the dermis. Again, the increased risk of scarring and pigment dyschromia makes this agent less attractive to the practitioner. If diluted and mixed with other complementary chemicals, this agent can be used effectively as a deep peeling agent.

Baker-Gordon solution (phenol)

Baker-Gordon peel produces the most dramatic results and is the most effective peeling agent currently used. The phenol produces a new zone of collagen that is thicker than that produced by laser. This solution is very effective in smoothing wrinkles related to aging and sun damage.

This advantage is countered by several disadvantages. The agent may produce premature ventricular contractions or more serious arrhythmia. A long healing time is required, with erythema occasionally lasting as long as 6 months. In addition, the potential for pigmentary changes, scarring, and infection are high with this peel. Despite the problems that may be encountered, a properly administered phenol peel is unmatched by the other peeling agents, and, for perioral wrinkles, the phenol peel even surpasses laser resurfacing. Although dramatic results can be achieved with the phenol peel, the risks and benefits should be weighed carefully before proceeding. Only experienced clinicians should attempt a phenol agent–based peel.

The Baker-Gordon solution is made of phenol 88%, 2 mL distilled water, 8 drops Septisol, and 3 drops croton oil. This formula penetrates into the middle reticular dermis and requires special monitoring devices, such as an ECG monitor and pulse oximeter, because of the potential of the phenol to cause arrhythmias.

Deep peels can be occluded or nonoccluded. The occluded method uses zinc oxide tape or another artificial barrier product to prevent evaporation of the phenol from the skin, thus enabling the solution to penetrate deeper.

Two variants of the Baker-Gordon peel are Litton's formula, which replaces Septisol with glycerin, and the Beeson-McCollough formula, which uses aggressive defatting and a heavier application of Baker-Gordon solution.

Patient Preparation

Preconditioning the skin is a useful adjunct to improving overall results. Trans-retinoic acid (Retin-A, Renova), an exfoliative agent, is believed to facilitate uniform penetration of the peeling agent and promote more rapid re-epithelialization. This may be applied nightly or every other night for several weeks prior to peeling, depending on the degree of skin irritation caused and patient tolerance. This promotes a thinning of the stratum corneum with shedding of keratinocytes while fibroblasts are stimulated.

Prior to the peel, the patient should thoroughly cleanse the face with nonresidue soap on the evening before and morning of the procedure. The patient is instructed not to apply makeup or moisturizers in the interim. The skin is cleansed immediately prior to the procedure to remove any remaining traces of makeup or oils. Either acetone or isopropyl alcohol may be used for this purpose. This step is essential to prevent uneven penetration of the peeling agent.

The patient may take 1-2 ibuprofen tablets (400 mg) 1 hour prior to the procedure.

Monitoring & Follow-up

The patient should be sent home with proper instructions along with advice to call should any complications arise. Skin preparation with bleaching creams and early reintroduction of these products in the immediate postpeel period are crucial to avoid postinflammatory hyperpigmentation in dark phenotypes.

Postoperative care is aimed at providing an ideal environment for moist wound healing. Initially, a generous amount of bland ointment (eg, white petrolatum, A&D ointment) is applied to the entire treated area. Patients are instructed to reapply the ointment throughout the day, any time the face feels tight or dry. As the outer layers begin to shed, the patient is allowed to shower and gently wash the face with nonresidue soap using fingertips only. After showering, the face should be patted dry and a new coating of ointment applied. Instruct patients to not pick at the face during the recovery period.

Rejuvenation regimen

Patients may treat the skin after a peel with agents such as tretinoin, hydroquinone, or an alpha-hydroxy acid. These may help the skin heal faster. Some practitioners use topical agents that contain platelet products or growth factors. While these products have been reported to improve wound healing in other clinical situations, no randomized controlled clinical trials presently support their use in this setting. Further research is ongoing in this area.

Coagulation and inflammation

The healing process after a chemical peel must be as rapid as possible to avoid infections that may deepen the wounds, extending the peel from superficial to deep, with increased risks of scaring. Deep peels may be prophylactically treated with antimicrobials, but superficial and medium-deep peels are simply kept moist with the application of petrolatum-based products.

In the early stages of wound healing, re-examine the patient within 48 hours and again every several days. Instruct patients to refrain from trans-retinoic acid, sunscreen, or makeup until the face is healed to the satisfaction of the treating physician.[13]

After reepithelialization, and when skin appearance is back to normal, a regimen of alpha-hydroxy acids, retinoic acid, bleaching creams, moisturizers, and sunscreens should be restarted. Sun exposure must be avoided for 6 weeks after the peel to minimize the risks of postinflammatory hyperpigmentation.

Production of controlled chemical burns of the epidermis and/or dermis results in exfoliation. The first phases of this process must be understood well to control the depth of penetration of chemical peelings. Phases are as follows:

  • The development of diffuse homogeneous erythema indicates epidermal penetration.
  • The development of white frost indicates coagulative necrosis of the papillary dermis.
  • The development of gray-white frost indicates coagulative necrosis of the reticular dermis.

In all these events, clotting factors are activated, as are monophages and lymphocytes. Inflammatory mediators are activated, such as C5a, leukotriene B4, and kallikrein.

Reepithelialization

Preventing scab formation is important for faster and more even healing. Biosynthetic occlusive dressings can be used to hasten the healing process for deep peels.

Granulation tissue

Granulation tissue usually appears the second day and consists of fibroblasts, inflammatory cells, fibronectin, glycosaminoglycans, and collagen. Reepithelialization occurs subsequent to this process.

Angiogenesis

This process begins with endothelial cell migration to the wound site and is essential for wound healing. The erythema following a chemical peel primarily is caused by the new capillary growth in the area.

Collagen remodeling

Collagen remodeling is the main reason that chemical peels are able to reduce wrinkles. The process of remodeling involves a reorientation of the collagen in a parallel fashion and begins as collagen is formed following the peel. Deposition of glycosaminoglycans in the dermis correlates with the efficacy of the peeling procedure.

Prolonged erythema

Patients usually do not report erythema because it generally subsides in 30-90 days, but sometimes erythema continues. Patients at increased risk are those taking oral contraceptive pills, exogenous estrogens, or other photosensitizing medications.

Prolonged erythema is usually not permanent, and topical hydrocortisone can be used to speed the healing process, as can a short course of systemic steroids. Other treatment options for hyperpigmentation include trans-retinoic acid, glycolic acid, or hydroquinone. Accompanying pruritus may be treated with oral antihistamines.

Acne

Some patients develop acne after a chemical peel. This usually occurs between days 3 and 9.

Cultures should be taken, and an antibiotic that covers gram-positive bacteria should be prescribed. If it is a true acne occurrence, then the appropriate topical treatment also should be started. If severe enough, isotretinoin may be initiated.

Milia

Small inclusion cysts, sometimes called milia, can appear in the healing process after a chemical peel. These usually appear about 2-3 weeks after reepithelialization and may be aggravated by ointments, owing to occlusion of the sebaceous glands.

Complication Prevention

Complications are not observed with superficial peels, nor are great benefits. In patients prone to hyperpigmentation, pretreatment and posttreatment with a bleaching agent are necessary. Sun exposure must be avoided, especially in these individuals. Deep peeling is a risk. Avoiding the ever-present risk of scarring is of paramount importance, but this is difficult when a marked result is desired and when little control over many of the variables of depth is possible. Conscientious attention to every detail of the peel and experience with the procedure are necessary. Hypopigmentation in white persons after a deep peel is almost universal and should be an accepted sequela of the procedure.

Many more complications and scars are recorded from trichloroacetic acid (TCA) peeling than from phenol peeling, perhaps because of the care with which phenol peels must be performed and the implied safety of TCA. Deep peels can be performed readily with TCA; take care not to peel too deeply. Other complications of infection, severe postoperative pain, and either too deep or too superficial a peel for the particular situation can be minimized with experience and vigilance.

Complications are more likely with darker skin types and certain peeling agents (eg, TCA).[14]

Pigmentary change

Pigmentary change is not an uncommon complication, especially with the deeper peeling agents. In some cases, the peeled area remains stark white. Taking proper precautions can help prevent undesirable pigmentary changes. Usually, patients with lighter complexions have a lower risk of hyperpigmentation, but genetic factors play an important role, and, sometimes, light-skinned patients with "dark genes" hyperpigment unexpectedly.

Skin priming using a combination of hydroquinone and tretinoin cream (Kligman formulation) before a superficial or medium-depth peel and early introduction of this preparation after deep peels reduces the rate of this complication.

Following chemical peeling, the skin is typically sensitive to the sun, which also may be a source of hyperpigmentation. Instruct patients to use sunscreen daily for 6-12 months following a chemical peel. Patients should also be educated in the appropriate application of camouflaging makeup.

Hypopigmentation is the result of melanocyte destruction or inhibition. Melanocytes originate from neural crest cells and do not possess the ability to regenerate or divide. Hypopigmentation is encountered most frequently when phenol is used as the peeling agent, which has led many to abandon phenol in favor of other agents. Hypopigmentation is more noticeable on darkly pigmented patients. Hypopigmentation may be difficult to assess until erythema has subsided, at which point the condition unfortunately becomes permanent. The line of demarcation between treated and untreated skin is usually the most noticeable. Prior to the peel, with the patient in the sitting position, note the position of the skin draping over the mandibular border. The peel may be feathered at this line of natural shadowing to create a transition zone. This may be performed by using a less concentrated formulation or by applying less of the agent in these regions. Camouflage makeup may help conceal this and other pigmentary disturbances.

Scarring

Scarring remains the most dreaded complication of chemical peels. The contributing factors are not well understood. By matching the patient and peeling agent properly, the risk of scarring can be decreased. In addition, to further decrease the risk of scarring, the patient should be advised to refrain from picking at the healing skin.

Patients with a history of keloids should not undergo medium or deep peels because of the risk of scarring. Medium and deep peels penetrate to the superficial and reticular dermis and, thus, may stimulate keloids. Weaker superficial peels that only exfoliate the stratum corneum or superficial epidermis can be used.

Delayed healing may lead to hypertrophic scarring, a devastating complication that requires close follow-up and aggressive early treatment. Topical or intralesional steroids, silicone sheeting, pressure application, and scar massage may improve outcomes. Scar excision or dermabrasion may be necessary in some cases of unsatisfactory results.

Infection

By using bacitracin for the medium and deep peels and cleaning the face with a povidone wash, the risk of infection is decreased.

Candidiasis infection also can develop, for which a short course of fluconazole can be used. Cultures need to be taken, and appropriate antibiotics should be administered.

Infectious complications are unusual but also demand vigilance and aggressive therapy with oral and topical antibiotics. Pseudomonas infections are treated by washing the face with equal parts water and distilled vinegar.

Toxic shock syndrome has been reported after a chemical peel.[15]

Herpes exacerbations are treated with oral and topical acyclovir until resolution. Most of these lesions respond rapidly and completely to this treatment and rarely cause scarring. Cold sores can be prevented with acyclovir (400 mg PO bid), beginning 2 days prior to the peel and continuing 7 days after the peel.

 

Technique

Approach Considerations

Chemical peels are divided into 3 categories depending on the depth of the wound created by the peel. Superficial peels penetrate the epidermis only, medium-depth peels damage the entire epidermis and papillary dermis, and deep peels create a wound to the level of the midreticular dermis. The depth of the peel is dictated by a number of factors, including the chemicals applied and their concentration, mode of application, and skin type and its condition. In general, the depth of the peel determines the patient's inconvenience during and after the procedure, the healing time, the rate of the potential adverse effects, and the results.[16] Several superficial peels are not equal in result to one deeper peel.

The images below depict a patient during and after a salicylic acid peel.

Men also request chemical peeling. This 56-year-ol Men also request chemical peeling. This 56-year-old man is in the process of a salicylic acid peel.
Same patient as shown above following a successful Same patient as shown above following a successful chemical peeling.

Application of Peeling Agent

The clinician can vary the number of coats depending on the depth of peel desired. The peel frost, or facial whitening indicating depth of epidermal damage, can aid in the determination of this number.

Most patients can tolerate a monthly superficial peel, while medium-depth peels can be performed at 6-month intervals if necessary.

Patient and equipment set-up

The peeling agent should be removed from its reservoir and put into a glass bowl. When performing a combination peel, pouring one agent at a time is advisable because of the ease in which the agents may be confused when poured into similar cups.

Cotton-tipped applicators may be used individually or put together to deliver more of the agent. Alternatively, 4 X 4-inch gauze may be folded into squares to apply the peeling agent. The gauze has the advantage of directing tactile pressure on the skin surface as the peel is performed.

Neutralizing agents are put in metal bowls to distinguish them from the peeling agents. One bowl contains a 1% sodium bicarbonate solution and the other contains cool water.

The patient should be resting comfortably in the supine position. The acid should not form pools in the facial folds nor drip from the face. The more acid the clinician applies, the deeper the peel.

Hair is removed from the face with a hair bonnet. The lips are coated with an occlusive ointment preparation, and cotton is put in each ear opening during the peel. If only the face is being peeled, the neck and shoulders are draped with towels. Eyewear is optional and often interferes with the area to be peeled; however, patients must understand that they should keep their eyes closed during the procedure. This is usually not an issue.

Contact time

The duration the peeling agent is in contact with the skin also helps determine the depth of the peel.

After the appropriate time has passed, neutralization is performed. Some chemical peels, such as salicylic acid and trichloroacetic acid, do not require a neutralization step because the skin neutralizes the acid. Glycolic acid peels must be neutralized.

Always wash the patient's face with water following the peel.

Density of adnexal structures

Recent radiation treatment can affect the density of adnexal structures. The reepithelialization process partially occurs from the adnexal structures; therefore, some clinicians advise that a punch biopsy be performed to verify their existence.

Occlusion

Products available, such as biosynthetic occlusive dressings, may decrease pain and speed healing. Examples include hydrogel membrane products, such as Vigilon (Hermal Labs, Delmar, NY); polyurethane membranes, such as Meshed Omiderm (Doak Dermatologics, Fairfield, NJ); and silicone membrane Silon II (BomMed Inc, Bethlehem, Pa).

Petroleum jelly and other occlusive ointments may, to a minor degree, act as an occlusive barrier.

Defatting

The skin should be cleaned, and excess fat should be removed with agents such as acetone, rubbing alcohol, Septisol, or a combination of these agents (see image below). Three parts alcohol with 1 part acetone works well.

The defatting process is important for the even pe The defatting process is important for the even penetration of the peeling agent. This patient is a Fitzpatrick type II, Glogau type I, using alcohol and acetone mixture to defat the skin.

A thorough defatting of the skin is necessary for proper penetration of the peeling agent because most agents are not lipid soluble.

Application

The patient should sit in a comfortable position, wear a disposable hair cap, and be instructed to keep the eyes closed during the procedure. A zinc oxide past should be applied at the lip and eyelid commissures.

The peeling agent can be applied with 4 X 4-inch gauze, cotton swabs, or the foam applicator that comes with the peel kit. Popsicle sticks are good applicators for the paste form. Apply the peeling agent in cosmetic units, beginning with the forehead and finishing with the chin. Feather the peeling agent into the hairline and the shadow of the mandible. Reapplication of the peeling agent may be necessary if the frost is uneven or is not white enough.

Frost

The change in coloration of the skin to a whitish tint is called frost. This represents the end stage of the chemical peel and shows that keratin agglutination has occurred.

Depending on the agent used, the white tint may vary from a brighter white in a superficial peel to a grayish white in a deep peel.

Neutralization

Neutralization of the chemical peeling agent is an important step once the clinician has achieved the proper depth of the peel, which is determined by either the frost or how much time has elapsed.

Neutralization can be achieved by applying cold water or wet, cool towels to the face following the frost (see image below). This soothes the sharp tingling discomfort caused by the peeling agent. Other neutralizing agents that can be used include bicarbonate spray or soapless cleanser. Peeling agents for which this neutralization step is less important include salicylic acid, Jessner solution, and phenol.

This 45-year-old woman has just completed her sali This 45-year-old woman has just completed her salicylic acid peel and will neutralize the peel with cold water.

Superficial Skin Peel

Superficial chemical peels are typically accomplished with use of alpha-hydroxy acids (AHAs). This group of chemicals is largely comprised of naturally occurring fruit acids, including glycolic, lactic, citric, tartaric, and malic acid. Arguably the most popular physician grade AHA used is glycolic acid, which is derived from sugar cane. Most formulations include concentrations of 50% glycolic acid or higher. After application, subsequent exfoliation occurs over several days. Over-the-counter AHA products contain 3-10% glycolic acid or one of the many other milder fruit acids. These formulations cause gradual exfoliation over several weeks and actually may be used as a pre-peel primer to potentiate the effects of a higher concentration peel. Unlike other peeling agents, penetration of glycolic acid is time dependent; thus, the agent is applied for a specific amount of time and then neutralized.

Many commercially available peels have applicators and are thickened with glycerin or similar substances so that they do not run. Avoid pooling of peeling solutions to ensure an even application. Only a thin coat is necessary, but it must be even.

The systematic application of glycolic acid with a sponge typically proceeds from one facial region to another, dividing the face into 6-8 regions and treating each in succession. The length of time that glycolic acid is left on the skin relates to concentration, with increasing concentrations achieving the desired results in less time.

Following application of glycolic acid, an initial erythema may become frankly red, often accompanied by edema. White patches subsequently develop, indicating epidermolysis with separation of the epidermis from the underlying dermis. Development of a frost indicates deeper depth of destruction into the dermis and is not desirable, as this is meant to be a relatively superficial peeling agent.

Removal of the glycolic acid is achieved by washing the face with water or neutralizing it with an alkaline solution such as sodium bicarbonate. Exfoliation typically occurs over several days, and re-epithelialization is complete within 7-10 days.

Multiple glycolic acid treatments may be required to achieve the desired results and should be spaced several weeks apart. Glycolic acid peels produce the least profound results but also are associated with the lowest frequency of complications.

Another agent used for superficial peeling is Jessner solution.[6] This solution is composed of 14 g of resorcinol, 14 g of salicylic acid, and 14 mL of 85% lactic acid mixed in enough 95% ethanol to bring the quantity to 100 mL. Jessner solution is usually applied with either cotton-tip applicators or sponge gauze. The Jessner solution is applied evenly with one or more coats to achieve a light but uniform frost. In some cases, 2-4 coats are necessary to achieve the desired level of resurfacing. The frosting achieved with Jessner solution typically results in the subjective feeling of heat with a mild discomfort that is easily controlled with a fan. After several minutes, a mild erythema appears with only faint evidence of scattered frosting over the skin surface.

Medium-Depth Peel

Medium depth peels are usually performed with trichloroacetic acid (TCA) in concentrations ranging from 20-35%.[17, 18] Depth of penetration is increased as concentration increases, with formulations of 50% having a well-documented ability to penetrate into the reticular dermis. Such concentrations are not recommended because of the extremely high risk of scarring associated with this depth of penetration. Currently, 35% TCA is considered the high end of a medium-depth peel formulation.

TCA works as a keratocoagulant that produces a frost or whitening of the skin, which is dependent on the concentration used. Vigorous rubbing of the agent, as compared with blotting, yields a deeper penetration. This technique is not time dependent, and the agent does not require neutralization.

Combination use of TCA and other peeling agents has been demonstrated to provide more effective skin resurfacing in some cases. For instance, application of Jessner solution immediately prior to use of 35% TCA has been shown to disrupt the epidermal skin barrier and promote deeper, more uniform penetration of the TCA. Similarly, Coleman has reported improved results with application of 70% glycolic acid prior to a 35% TCA peel.

The systematic application of TCA with a sponge also involves treating the face in a succession of 6-8 regions. TCA application is associated with an intense burning that usually resolves within 30 minutes. Administer appropriate analgesia prior to the procedure and consider regional nerve blockade with lidocaine. Patient comfort may also be improved by having a fan to cool the face and by applying sponges soaked in iced saline prior to moving from one facial region to another.

During the procedure, if the frosting is not uniform or complete, reapplication may be performed until frosting of a desired plateau is reached. Once completed, exfoliation proceeds for several days, and re-epithelialization is complete within 10-14 days.

Deep Skin Peel

The standard-depth deep chemical resurfacing procedure is a phenol peel. Phenol peels may be performed with various formulations, such as pure phenol (which is really 88%) or phenol mixed with soap, water, croton oil, and sometimes olive oil. These formulas have such names as Baker-Gordon, Venner-Kellson, Maschek-Truppman, and Grade. The classic Baker-Gordon formula is composed of 3 mL of United States Pharmacopeia (USP) phenol, 2 mL of tap water, 8 gtt of liquid soap, and 3 gtt of croton oil.

Phenol causes keratolysis and keratocoagulation. In contrast to other agents, increasing the concentration of phenol actually decreases the penetration up to a point. This is because the ensuing destruction forms a barrier to further penetration of the chemical. Pure phenol does not penetrate as deeply as the various formulations. Occlusion with a waterproof mask is reported to deepen the level of the peel, which increases the time required to fully re-epithelialize and increases posttreatment erythema. Following the peel, many physicians now apply a thick layer of petroleum jelly or other equivalent agent. Predictable but less profound results are produced, and penetration is less. Similar to trichloroacetic acid (TCA), the time spent applying the agent and the amount of sponge strokes used are proportional to the depth of penetration. The addition of croton oil to the various formulations as a skin irritant also allows deeper penetration.

Although phenol produces the most remarkable resolution of actinic damage and wrinkling among the various chemotherapeutic agents, it also possesses some of the more significant morbidities. Many have abandoned phenol in favor of other agents or laser resurfacing.[19] Marked hypopigmentation may result following the use of phenol and is correlated with the depth of penetration, use of the Baker-Gordon formula, and addition of croton oil. Hypopigmentation may occur in all skin types, noticeably lightening the skin of patients with darker skin and making lighter-skinned patients appear waxy or pale. A clear line of demarcation may be present between treated and untreated skin.[18]

Phenol causes an intense burning upon application that may last 4-6 hours, which is much longer than the discomfort associated with other peeling agents. Administer appropriate analgesia prior to the procedure and consider regional nerve blockade with lidocaine. Patients also must be provided with sufficient oral analgesics and anxiolytics for use at home following the peel.

The toxicity of phenol may be significant. Phenol is absorbed through the skin, metabolized by the liver, and subsequently excreted by the kidneys. Some practitioners preload the patient with fluids to facilitate renal clearance. Overdoses may injure the liver and kidney and may lead to myocardial irritability, including arrhythmias. For this reason, monitor patients with telemetry during the procedure and in the immediate recovery period. The face is again divided into 6-8 regions, but 20 minutes must be allowed to elapse between treating subsequent regions. This allows for some degree of ongoing metabolism and helps avoid a toxic systemic dose.

The length of time of peeling usually is similar to that for superficial peels, but because of the depth of peel, redness may be present afterward for 6-8 weeks.

Follow-up care is frequent, with visits every 2-3 days until re-epithelialization is complete, and then every week until the redness is gone.

Avoid steroids so as not to interfere with the maturation and thickening process of the new skin.