What is a chemical peel?
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.
Thus chemical peel is a technique used to improve the appearance of the skin on the face, neck or hands. A chemical solution is applied to the skin that causes it to exfoliate and eventually peel off. The new, regenerated skin is usually smoother and less wrinkled than the old skin. The new skin is also temporarily more sensitive to the sun.
Chemical peels are currently classified according to the depth of penetration and injury caused. The lower the pH the deeper the penetration, the higher the percentage of free acids the larger the injury. The balance and combination of the two is what defines the peels strength and effect.
Superficial peels (also called lunch time peels) penetrate to any depth within the epidermis, down to the stratum basale. Superficial peels have a relatively safe pH level (usually above 2.5) and level of free acids and can usually be administered by trained skin therapists both at aesthetic clinics and spas as well as healthcare professionals. There is typically very little to none discomfort and no down time for the patient. These types of peels can be taken once a week in the beginning when addressing specific needs and conditions and once the results are obtained, 4-6 week intervals as maintenance treatment.
Medium Depth Peels
Medium-depth peels penetrate through to the papillary dermis and are lower in pH value (typically between 1 and 2.5) and are most often done by healthcare professionals as the treatment requires good understanding of skin anatomy, application training and often registration with health authorities. Stinging sensation may be strong at application and post application and recovery takes from a few days to a couple of weeks. These peels can be performed at 2-3 weeks interval – particularly if taken as form of treatment and once the results are satisfactory, then as maintenance 4-6 weeks interval.
Deep peels penetrate down to the level of the reticular dermis and are thus capable of removing most of the skin tissue if assessed to be needed and appropriate. Deep Peels are the lowest in pH value (usually below 1) and highest in free acid content. They are always done by healthcare professionals and require good understanding of skin anatomy, application training and registration with health authorities. They are the most painful at application. Recovery varies according to the depth and level of injury from a couple of weeks up to several months. These types of peels, while extremely effective, are usually done at much less frequent basis, from a few times per year to once in a life time – again depending on the depth and level of injury caused.
Types of Peels by chemical components
Alpha-hydroxy acids such as lactic acid, mandelic acid, glycolic acid, citric acid, tartaric acid or another acid is used to penetrate only the outer layer of skin to gently exfoliate it. The treatment is used to improve the appearance of mild skin discoloration and rough skin as well as to refresh and rejuvenate the face, neck, chest or hands.
Alpha hydroxy acids (AHAs) have been applied as topical preparations and peeling agents for more than forty years. These peels are seen 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. The most commonly used AHA is glycolic acid, many published clinical studies have reported the effects of AHAs in treating photo-aging.
The main mode of action of AHAs is to damage the desmosomal attachments between corneocytes, and reduce corneocyte cohesion. 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. 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.
Glycolic acid peels are formulated in strengths all the way 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.
The AHA lactic acid is sometimes used for chemical peels between 15% and 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.
Another type of hydroxy acid peel is a Beta-hydroxy acid based peel. 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 known to be able to penetrate hair follicles and sebaceous glands and exhibits comedolytic properties. This makes it very useful and relatively gentle peel for management of acne and oily skin. The application of salicylic acid as a peel solution generates a frost on the skin when applied, which is a precipitate and should not be confused with epidermolysis or precipitated dermal protein.
Retinoic acid Peels
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. 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 retinoin for a period of four to six months. Vitamin A peels and peel enhancers may enhance the effects of other peel types; for example, salicylic and glycolic acid peels enhance desquamation and do not necessarily need to be removed post application as many of the other types of peels do (depending on the manufacturer).
Medium peel: Glycolic or trichloroacetic acid is applied to penetrate the out and middle layers of skin to remove damaged skin cells. The treatment is used to improve age spots, fine lines and wrinkles, freckles and moderate skin discoloration. It also can be used to smooth rough skin and treat some precancerous skin growths, i.e. actinic keratosis.
Deep peel: Tricholoracetic acid or phenol is applied to deeply penetrate the middle layer of skin to remove damaged skin cells. The treatment removes moderate lines, age spots, freckles and shallow scars. Patients will see a dramatic improvement in skin appearance. The procedure is used on the face and only can be performed once.
A third type of chemical Peels is a TCA based peel.
TCA is a non-toxic chemical (trichloracetic acid), which has been used to perform skin peels for over 20 years. It is a relative of vinegar (acetic acid.) When TCA is applied to the skin, it causes the top layers of cells to dry up and peel off over a period of several days to one week. When the old skin is peeled off, it exposes a new layer of undamaged skin, which has a smoother texture and more even color.
Depth of TCA Peels:
Superficial or “light” peels remove only the top layer, mostly the layer of dead skin called the stratum corneum. Progressing from medium to deep peels, the layer of skin removed is greater with each increase in strength of the peel solution. Lighter TCA peels are usually done in a series of 2 or 3 for best results. This is similar to other light peels that usually involve hydroxy acids such as glycolic, salicylic, or a mixture of other hydroxy acids.
Some TCA peels is blended with lactic acid which is an alpha hydroxy acid (AHA) and helps to reduce the appearance of aging, and they can be an especially good remedy against fine lines, wrinkles and other signs of premature aging from sun damage. Read more about AHA in AHA Peels
Additional key ingredients:
- Kojic acid (has a lightning effect on skin and therefore treats melasma, the appearance of scars, sun damage and age spots)
- Azelaic acid (helps to reduce redness, acne, treats rosacea and uneven skin such as wrinkles and fine lines)
- L-ascorbic acid (known for its purest form of vitamin-C and rejuvenates collagen fibers which results in firmer and more even skin)
- Arbutin (lightens the skin and reduces the skin’s melanin production)
TCA peels are most commonly used:
- to reduce brown spots and age spots
- to improve the texture of leathery, sun damaged skin and impart more glow
- to improve melasma
- to treat highly inflamed acne
- to reduce fine lines
- to improve rosacea
Jessner’s peel solution, formerly known as the Coombe’s formula, was pioneered by Dr. Max Jessner, a German-American dermatologist. Jessner combined 14% salicylic acid, lactic acid, and resorcinol in an ethanol base. It is thought to break intracellular bridges between keratinocytes. A Jessner Peel is a medium-depth chemical peel that works to improve skin health by helping remove and heal skin damage that is more extensive than regular “wear and tear.”
Some of the benefits of the Jessner Peel is improved appearance of acne, blackheads, and enlarged pores, oil reduction, improved rosacea and reduce the appearance of acne scar.
- Salicylic Acid: This is a beta hydroxy acid (BHA) and is oil-soluble, making it ideal for acne prone or oily skin types. Salicylic acid works to dissolve dirt and sebum that clog pores and cause blemishes, blackheads, or whiteheads. It is also very effective at reducing or balancing oil production so skin will be less likely to suffer breakouts.
- Lactic Acid: Like glycolic acid, lactic acid is an alpha hydroxy acid (AHA) which is an excellent exfoliator and very effective at lightening hyperpigmentation or dark spots. It also stimulates collagen and elastin production, and will soften the epidermis to allow for better penetration.
- Resorcinol: This chemical helps lift away the top layer of skin to reveal the smoother layer underneath and also acts as a sterilizing agent due to it antiseptic properties.
The peel is not recommended for those in the higher end of the Fitzpatrick scale, since the lightening agents may leave areas of hyper-pigmentation. Salicylic acid is a component in aspirin so Jessner Peels should not be used by anyone suffering with an aspirin allergy. Peels should also be avoided if you are pregnant or nursing.
Over the years the Jessner peel has been improved by addeting new ingredients to the peel, these peels are called Modified and Enhanced Jessner’s Peels.
- Kojic acid (has a lightning effect on skin and therefore treats melasma, the appearance of scars, sun damage and age spots)
- Hydroquinone (effective ingredient for fading uneven skin tone, brown or dark spots, and lightening skin)
- Citric acid ( an AHA which correct fine line and dark spots, shrink pores and brighten skin)
Phenol peels are the deepest type of chemical peel. They penetrate the skin deeper than AHA Peels and TCA Peels to address more serious imperfections such as blotchiness, coarse wrinkles, and acne scars.
Phenol chemical peels are the most aggressive type of skin peels, this peels often . A phenol peel is an effective remedy for severely sun damaged skin, coarse wrinkles, scars, and even pre-cancerous growths. The chemical solution used in phenol peels removes damaged outer layers of skin to reveal a new, smooth layer of skin. Because a phenol peel uses carbolic acid to treat the skin, the procedure is not suitable for treating selected areas. It must be used on the full face.
Phenol peels are performed under carefully monitored conditions in a doctor’s office. The patient is put under sedation, and local anesthesia is used to ease the discomfort associated with this advanced chemical peel. The chemical solution also contains anesthetic that numbs the skin.
Phenol’s bleaching effect make phenol peels less than ideal for those in the higher scale fg the Fitzpatrick. A phenol peel provides dramatic rejuvenation. After healing is complete, the skin is much clearer and luminous, more elastic, and the appearance of deep wrinkles and severe discoloration is significantly reduced. A deep chemical peel can make you look younger, and the results can last decades without special care other than protection against sun exposure.
Phenol is on a list of ingredients that is not recommended in the EU, due to the dangers and side effects. The recovery time is up to 10 months and the patient should avoid exposing the treated skin to the sun and always use sun block.
When is a chemical peel appropriate?
If you are considering a peel, the first thing for you to do is to speak about it with your skin specialist who is qualified and trained to conduct chemical peels to see if you would be a candidate for it. Chemical peels are used to treat a number of conditions including:
When to be careful and who is not a candidate
Generally light-haired and fair skinned people are the best candidates for chemical peel. The procedure does not necessarily work as well on dark-skinned patients. The procedure is not recommended for individuals with infections, cut or broken skin, sunburns or active Herpes simplex 1 sores. Other counter-indications include patients who are:
- Nursing or pregnant.
- Have taken Accutane in last six months.
- Have active skin disease such as psoriasis, eczema, dermatitis or rosacea.
- Have used Retin-A, Renova, prescription skin care products, products that contain ascorbic acid, bleaching or skin-lightening agents or other acid-based products in the last 48 hours.