Understanding Skin Care Ingredients
Skin Care Ingredient Essentials
During the past few years, many new and effective skin care therapies have become available to correct and protect against the effects of aging. Despite the myriad of skin care products on the market, all of these products fall under just a few categories: Sunscreens, Moisturisers, exfoliants, retinoids, antioxidants, bleaching agents, cell growth factors, and “herbal/other”.
- Alpha Hydroxy Acids (AHAs)
- Human growth factors
- Mechanical Exfoliation
- Beta Hydroxy Acids (BHAs)
- Bleaching Agents
- Vitamin C
- Botanical Agents
- Exfoliation with Microdermabrasion and Peels
- Chemical Exfoliation
Although skin loses about 1% of its collagen and elastic tissue per year after age 25, it is the effect of ultraviolet light from the sun that causes most of the visible effects of “aging” skin. Regular use of an effective sunscreen is the single most important step one can take to maintain healthy, youthful looking skin.
Ultraviolet radiation (UVR) from the sun damages proteins, elastin, and DNA in the skin, and is the major cause of skin aging and skin cancer. Short wavelength ultraviolet rays, or UVB, are absorbed primarily in the upper layers of skin (the epidermis), while the longer wavelength, or UVA, rays are more penetrating, causing damage in the second layer of skin (dermis). UVB damage to DNA in the cells of the epidermis is the most common cause of skin cancer, while UVA damages the delicate collagen and elastic fibers in the dermis, causing loss of elasticity, wrinkling, discoloration and telangiectasia (“broken veins”). Unlike UVB, UVA is only partially blocked by glass and atmospheric water vapor (clouds), and is less affected by time of day, season, and geography. Only UVB rays induce tanning, which is a protective response to radiation damage to the epidermis; the longer wavelength UVA rays such as those used in tanning booths, do not induce a true protective tan.
There is no such thing as a safe tan! The presence of a tan is evidence that the skin has been damaged by ultraviolet radiation. Damage induced by ultraviolet radiation is cumulative over a lifetime, and is not related to activity at the time of exposure (for example, 100 3 minute exposures while running errands is equivalent to 5 hours of continuous exposure lying on a beach).
Although it’s almost impossible to eliminate exposure to UVR entirely, it can be minimized by protective clothing and proper use of an effective sunscreen. Effective protection from photo aging UVA is more demanding than that required from the cancer – causing UVB. The commonly used “SPF” refers only to UVB rays, and does not translate into UVA protection. Most pharmacy sunscreen preparations are effective UVB blockers, but allow most of the more penetrating UVA energy to pass through and age the skin.
There are two types of sunscreens: chemical and physical blockers
Traditional chemical sunscreens act primarily by binding to skin protein and absorbing UVB (280 – 320nm) light, and most are based on para-aminbenzoic acid (PABA or its derivatives such as Padimate O), cinnamates such as methoxycinnamate, and various salicylates (Octyl salicylate). Many commercial preparations contain weaker UVB/UVA absorbers, including benzophenones (Oxybenzone, Benzophenone), dibenzoylmethanes, and anthraline (Menthyl anthralinate) derivatives, which have a limited UVA (320-400nm) absorption as well. Octocrylene is a weak but stable UVB absorber used to protect other agents from degrading. Avobenzone (Parsol-1789) is a benzophenone with fair UVA protection, but it degrades readily and tends to be irritating. All of these organic sunscreens (especially PABA) can cause allergic or irritant contact dermatitis and no single organic agent gives complete protection from UVA and UVB radiation.
Physical agents, or sunblocks, act as physical barriers which reflect or scatter radiation like a t-shirt or a hat. Direct physical blockers include metal containing compounds such as iron, zinc, titanium and bismuth. Iron oxide pigments are incorporated in many cosmetics, and provide protection from not only UV radiation, but visible and IR (Infrared) as well. Zinc Oxide (ZnO) and Titanium Dioxide (TiO2) are highly reflective white powders but their main problem is they are often thick and uncomfortable to wear, giving rise to a unattractive whitish sheen when applied to the skin. Traditional ZnO sunblocks such as those commonly used by lifeguards are opaque white, but when the particle size of the zinc oxide or titanium is decreases to 100-150 nm (nanonised) they transmit visible light while retaining their UV blocking properties, rendering the sunblock invisible on the skin. Nanonised Zinc is more stable than nanonised titanium dioxide and offers better UVA protection. Not only are physical blockers superior to chemical blockers but they also cause much less irritation to people with sensitive skin.
Allergic or irritant contact dermatitis or photoxicity do not occur with these agents. Currently, preparations containing at least 2-6% submicron Zinc Oxide are he preferred sunscreens for comprehensive UVA protection.
When choosing a sunscreen preparation it is important to make sure it covers both UVA and UVB light. Most sunscreens only cover UVB, only a few cover UVA light. Suncreens ingredients that block UVA light include Zinc Oxide, titanium dioxide, avenobenzone (parsol 1789), ecamsule (meroxyl SX), bemotrizinol (tinosorb) and helioplex ( neutrogenia patent)
Other ingredients that may be found in sunscreens include “extender” substances such as mica or talc, and organic polymers such as micronized nylon and chitin. Aside from improving the “feel” of the sunscreen preparation, these substances can help scatter energetic photons and act as a “scaffold” for the active sunscreen ingredients, increasing the effective thickness of the active sunscreen layer.
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Hydration and humidity are critical yet often overlooked elements of skin care. Cooler weather brings lower humidity and higher wind speeds, both of which increase waster loss through the skin. Adequate water intake and humidification of the home will help prevent dry, itching and flaking skin especially during the heating season.
Moisturisers are preparations that relieve the signs and symptoms of dry skin. If the skin is not dry, such as in the summer months, or in the patients with oily skin, a moisturizer need not be used for its own sake. A thick, occlusive moisturizer may be suitable for dry, chapped hands, but may clog pores on the face. Facial moisturizers should be humectant, or water binding, to increase the water content of the non- living outer layer of the skin.
Moisturisers usually incorporate Emollients to smooth the skin surface by working their way into the non-living outer layers of the skin, filling spaces between the layers and lubricating, and Humectants to help skin cells absorb and retain moisture in these layers.
Commonly used emollients include mineral oil, petrolatum, shea butter, cocoa butter, and animal oils including squalane, mink oil, emu oil, and lanolin. Long-chain fatty acid esters such as myristates, palmitates, cetyrates, strearates, various triglycerides, and cholesterol and derivatives are often include in the formulation as thickening agents.
Humectants often used in moisturisers include glycerin and glycol derivatives, such as propylene or polyethylene glycol (PEG), hyaluronic acid and its salts, mono- and polysaccharides such as fructose, sorbitol, polysorbates, cellulose, and glucosamine and hyaluronates, phospholipids including ceramides and sphingolipids, amines such as triethanolamine and diazolinyl urea, and silicones such as dimethicone, which also has excellent emollient properties and contributes to the “feel” of the moisturizer.
Despite the common belief that moisturisers are the mainstay of skin care, they are often unnecessary and may even be detrimental in some patients, especially those with oily or especially sensitive skin. All moisturizers have the potential to clog pores and cause irritation, and should only be used when the skin is truly dry. It is important to realize that moisturizers do not stop aging.
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AHAs, or “Fruit acids” are mild organic acids present in various foods. The most commonly used AHA is Glycolic Acid, derived from sugar cane; other AHAs used therapeutically include Lactic Acid (milk), Citric Acid (oranges, grapefruits, lemons), Tartaric Acid (grapes), Pyruvic Acid (bananas and other fruits), and Malic Acid (apples). AHAs are commonly used in low concentrations in cleansers, moisturizers, and toners, and in higher concentrations as light peel solutions.
The principal effect of AHA;s is to loosen dead skin cells in the outer layers of the epidermis, increase cell turnover, and increase the deposition of glycosaminoglycans in the upper dermis. This refines the texture and appearance of the skin, unclogs pores, and weakens the epidermal barrier to allow effective penetration of other topical agents, including moisturizers, retinoids, bleaching creams, antioxidants, ect.
AHA;s are also hypergolic, or water binding, and thus are outstanding hydrating agents. The net effect of this exfoliation and hydration is smoother and healthier looking skin.
The beneficial effects of AHAs have been known since antiquity. Legend has It that Cleopatra bathed in sour milk and Marie Antoinette in champagne, containing lactic and tartaric acid, respectively. A typical AHA regimen would include at least two weeks of daily use of a home care product, followed by a series of 3 – 6 light facial (lunchtime) peels, spaced about 2 weeks apart. Other topical agents, such as bleaching creams, retinols, etc. may be added gradually after the first peel. Some stinging or redness is expected at first, but will improve as the skin adapts to the AHA. If redness or irritation recurs as other skin care treatments are added (such as bleaching agents, retinoids, ect.), or as exfoliation progresses, a milder AHA can be used, or the frequency of application can be decreased
The efficacy of AHAs is directly related to the amount of free acid present in the product. A low pH (pKa) means more free acid, and greater penetration into the dermis, but with a greater potential for adverse reactions. AHA products with a pH higher that 4 are ineffective exfoliants; those with a pH of less than 3 are only available from skin care professionals. Many products are prepared with a high concentration of an AHA, but are “buffered” with an alkaline solution such as NaOH or NH4OH, decreasing the acidity (raising the pH) and irritation potential of the product. This is why some products containing as little as 2% AHA can be more effective (and more irritating) than products containing 20% or even more AHA.
Occasional exfoliation may be useful, it will refresh the skin surface and brighten the skin by removing the top layer of dead skin. However, if you overexfoliate too frequently or too aggressively, then you will cause damage to living cells. This will leave you with red irritated skin and eventually that may produce long term skin damage and exhaust the skins long term capacity to regenerate. This is known as the Hayflick limit. Hayflick states that there is a limit to the number of times the cells can regenerate during their lifetime.
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There is only one clinically important beta hydroxyl acid, Salicylic Acid. This substance, a close relative of the common aspirin, is repelled by water and highly soluble in fats and oils, and is used primarily to open comedones and expedite penetration of less fat soluble AHAs into oily skin. It’s most commonly used in combination with AHAs in light peeling solutions particularly for acne.
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Retin-A (retinoic acid or tretinoin), originally approved for the treatment of acne, has been shown to be effective for the prevention and treatment of sun-induced skin aging. Effects include increased collagen and circulation in the upper or papillary dermis, reduction in hyperpigmentation and brown spots, increased cell turnover in the upper layers of skin, including blackheads and pores, and an overall appearance in the improvement of the skin. These beneficial effects of retinolds are related to the dose and duration of use, with the optimum effect noted after at least a year of treatment. Unfortunately, topical retinolds tend to be very irritating, with most patients experiencing redness, flaking, and increased skin sensitivity. Increased sensitivity to the sun is another drawback of retinold therapy. A less well known drawback of retinold therapy is that prolonged use (>4 months) is needed to produce significant improvement in the appearance of the skin.
Newer “Third Generation” topical retinoids, such as Differin (adapalene) and Zorac (tazarotene) are currently approved for treatment of acne and photoaging. Avage (tazarotene) has been acepted as the “gold standard” topical retinold for cosmetic use. Like other retinolds, it exerts its action on cellular receptiors, and appears to be somewhat less irritating and photosensitizing, as well as more effective for both acne and photoaging, than Retin-A.
Some of the effects of Zorac include:
- improvement of collagen synthesis and repair
- decreased production and aggregation of melanosomes, thereby improving pigmentary abnormalities
- increased production of ground substance (hyaluronic acid), thus “plumping” the skin and improving wrinkles
Like other retinoids, Zorac needs to be properly incorporated into a skin care regimen to avoid unnecessary irritation and maximize its effects.
Retinol, is converted to retinoic acid (tretinoin, Retin-A) in living cells. When applied to skin, Retinol penetrates better than retinoic acid, and does not produce the same irritating effects. Although its clinical effects are not as dramatic as retinoic acid, retinol is available without prescription and has been incorporated into many skin care products. Retinol is 100 times weaker than retinoic acid. Regular exfoliation with AHAs may enhance the effects of Retinol.
Retinaldehyde is another form of vitamin A that is 10 times weaker in strength than retinoic acid but probably has the same clinical effect as retinoic acid preparations. Its advantage is that its over the counter and has fewer side effects than retinoic acid. However it is more expensive than both retinol and retinoic acid. Its expense prevents it from being used widely in skin care products. Some high end skin care ranges contain retinaldehyde in their preparations.
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Hydroquinone is the most commonly used agent for “bleaching” brown marks, melasma, ect. Acting to block the formation of the skin pigment melanin, hydroquinone’s bleaching activity is reversible, that is, the pigment returns when the hydroquinone is discontinued. Kojic acid, extracted from mushrooms, is a slightly less effective agent. Either may be compounded with AHA’s. As with any bleaching agent, aggressive exfoliation and sun protection are necessary for good results. Either agent may produce redness and irritation, especially with prolonged use. Arbutin, extracted from bearberries (licorice), also is an inhibitor of melanin production, and is often used in skin care products as a soothing agent. Using bleaching agents without aggressive sun protection is a recipe for failure.
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The ability of the body to turn nutrients into energy involves Oxidation, in which nutrients are “burned” in a controlled manner to provide energy for growth and repair. An inevitable result for this process is the production of free radicals. Free radicals may also be produced by processes other than oxidation, most notably from ionizing solar radiation, including UVA and UVB.
A free radical is an atom or molecule containing an unpaired electron. Elevated to an excited state by some energetic reaction, the unpaired electron will seek to attain a lower energy state by pairing up with another electron or electron rich molecule, as with 2 highly reactive free oxygen atoms pairing up to form the stable O2 molecule. The most significant free radicals in biological systems are those involving oxygen, such as the superoxide (HO2) and hydroxyl (OH) radicals, produced during normal cellular respiration. By providing an electron, antioxidants may convert the free radical to a non-radical species, or to a more stable radical form.
Free radicals play an indispensable role in normal biological processes, but these extremely reactive molecules can cause damage to normal cellular processes and structure, and are a key contributor to the aging process. To defend against damage from free radicals produced in the normal course of cellular function, biological systems have evolved Antioxidants.
Biologic antioxidant systems include:
- Antioxidant enzymes such as superoxide dismutase, catalase, peroxidase
- Dietary antioxidants such as the tocopherois, carotenes, ascorbic acid, alpha-lipoic acid, glutathione, resveratrol, polydatin, ect. These are found in berries, red grapes,avocado, cucumber, broccoli, garlic, spinach, carrots and celery
- “solid state” antioxidants such as melanin
- DNA repair systems
Antioxidants are a diverse group of chemical compounds that have evolved over billions of years to allow life to flourish in the presence damaging UV light and an oxygen-containing atmosphere. Energy released by normal cellular metabolism is contained and controlled by antioxidants, much as the energy released by an automobile engine is contained and controlled by the cylinder walls, valves, transmission, ect.
Antioxidants are often incorporated into skin care products to protect the skin from free radical damage produced by normal aging, pollution, and UV radiation from sun exposure. Many of these antioxidants are available as dietary supplements, or “nutraceuticals”, and have been demonstrated to have plethora of beneficial effects, at least in the laboratory. Their role as topical agents is less well documented.
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The most used topical antioxidants is Vitamin C essential for collagen syntheses and UV protection .Vitamin C, or ascorbic acid, stimulates collagen production, and exerts its antioxidant effects by quenching free oxygen radicals produced by ultraviolet radiation and by assisting Vitamin E in protecting cell membranes. Although the photo protective effects of L-ascorbic acid are well established, it readily degrades in the presence of sunlight, and does not penetrate the skin well, except as high concentrations and high acidity. Vitamin C esters, although more stable, have limited bioavailability when used topically..
- Vitamin E: The active form of Vitamin E, alpha tocopheol, has been shown to inhibit enzymes which promote breakdown of collagen and to protect cell membranes from oxidation (lipid peroxidation). Contrary to popular opinion, topically applied Vitamin E has not been demonstrated to have a significant effect on scar formation and is very unstable in light.
- Coenzyme Q10: Also know as ubiquinone, Coenzyme Q10 is a component of all cell membranes, and is a vital component of the electron transport chain. It acts to shuttle electrons in normal metabolism, trap free radicals, and help regenerate other antioxidants present in the cell, especially Vitamin E. .
- Spin Traps: Spin traps are special molecules that can trap and detoxify damaging free radicals which age the skin. They are commonly incorporated into preparations which include other antioxidants
- Idebenone: Similar in structure to Coenzyme Q10, idebenone is a more efficient free radical scavenger, and functions incidentally as an electron carrier. It has been used in Europe for years as an anti-aging compound, as well as cognition enhancer in patients with Alzheimer’s disease and other neurologic disorders. Idebenone is the most potent topically antioxidant available and has been shown to reduce the appearance of fine lines and wrinkles, decrease skin roughness, and even out skin tone but it is expensive and can cause contact dermatitis.
- Alpha-lipoic acid (thioctic acid) is a potent antioxidant normally found inside cells, acting to protect delicate cellular membranes from free radical damage during normal cellular respiration
- Resveratol and Polydatin deserve special mention as the substances responsible for the “French paradox”; that is, the very low incidence of heart disease in residents in Southern France, despite high rates of smoking and a diet high in saturated fats. This effect has been attributed to a high consumption of red wine, a rich source of resveratrol.
Resveratrol and Polydatins are glucopyranosides found in many fruits and vegetables, the highest concentrations being found in grape skins, which synthesize these compounds in response to exposure to UVA/B and fungus Biologic activities of these glucopyranosides include potent free radical scavenging activity, with cardio- and neuroprotection and inhibition of lipid peroxidation similar to that seen with Vitamins C and E.
- Boldine – Boldine occurs abundantly on the leaves and bark of boldo (Peumus boldus), a widely distributed native tree of Chile.
- Glutathione – is found in almost all living cells in our body. Its main role is to strengthen the immune system, act as the body’s master antioxidant, control the function of other antioxidants (Vit C and E)
- Beta-Carotene: occurring in many vegetables, notably carrots and tomatoes, this compound helps minimize lipid peroxidation of cell membranes, and is especially effective at quenching UV-induced singlet oxygen.
- Anthocysnins: these bioflavonoid compounds, extracted from pine bark (“Pycnogenol”) and grape seeds actively quench free radicals and potentiate the effect of Vitamins C and E
- Green Tea extract contains antioxidant poyphenols which have been shown to protect against redness and swelling induced by UV radiation.
- Ginko Biloba: Often used as a dietary supplement, Ginko Biloba leaves contain as assortment of polyphenols and bioflavonoid. In addition to antioxidant effects, Ginko Biloba extracts has been demonstrated to increase collagen production in cultured fibroblasts, although this effect has not been conclusively demonstrated in living skin.
Harvested as a by-product of tissue-cultured human skin, various human growth factors have been incorporated into topical preparations, the best known of which is TNS Recovery Complex. These substances, essential for wound healing and recovery, have been shown to reduce the number and depth of wrinkles and fine lines, as well as improve skin texture and elasticity when used over time.
Some of the growth factors found in tissue culture media include transforming growth factor beta (TGF-B), vascular endothelial growth factor (VEGF), keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF). Other substances found in cell culture media include matrix proteins, procollagens, interleukins, cytokines, and other compounds with biologic activity. As with any topical preparation, penetration through the skin limits the bioavailability and effect of these substances.
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Herbal and Botanical ingredients have been used to improve the appearance of skin since time immemorial, and although the role of botanical substances in medicine is well known, the effect of these substances used on the skin is less clear. They are most often used in “natural” or “holistic” skin care preparations for their scent and feel, as well as for marketing purposes. In most cases there’s little scientific basis for their efficacy, with little or no standardization of dose or concentration, and some of these substances may cause sensitivity, allergy, or dermatitis. The decision to use such preparations is best left to individual preference.
Many of these may be toxic, or interact with other drugs when taken internally, and cause irritation, dermatitis, and/ or photosensitivity when used topically. A lack of standardization of the various preparations further complicates any assessment of their efficacy.
- Hammamelis (witch hazel)
- Calendula officinalis (calendula)
- Bromelain (pineapple) is an enzyme extracted from pineapple stems, which when taken internally, may help decrease swelling and speed the resolution of bruising
- Arnica Montana (arnica) has been used topically to reduce or minimize bruising and swelling, and as a general smoothing agent. Although studies have demonstrated these effects in the laboratory, rigorous clinical trials on patents have shown no significant effect.
- Aloe Vera (aloe) has been demonstrated to enhance wound healing in patients with frostbite, and superficial abraded wounds, although some studies have shown delayed wound healing, especially in deeper or complex abraded wounds.
- Echinacea purpureae (purple coneflower)
- Symphytum officiale (comfrey) another traditional helaing/soothing agent for swelling and bruising, comfrey has demonstrated liver toxicity and carcinocenicity in laboratory rats, and is not recommended for internal use.
- Mentha piperita (peppermint oil) is a mild antibacterial and antifungal agent, and can exert a cooling effect on the skin.
- Melaleuca alternifolia (tea tree oil) may antibacterial and antifungal when used topically.
- Solanum Dulcamara (bittersweet)
Copper is found in most biologic systems, and acts as a cofactor in collagen and elastin production, production of new blood vessels, and disposition of glycosaminoglycans in the skin. Unlike copper sales, which are highly toxic, copper atoms are stabilized with peptide complexes (short lengths of protein molecules) to assist delivery into the skin. Copper peptide complexes used topically have been shown to increase procollagen formation and may help retard some signs associated with skin aging.
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The principal function of the skin is to act as a two-way protective barrier. The epidermis is the outermost laser of skin, constantly producing new cells which are gradually shed at the skins outer surface. This non-living outer layer (stratum corneum) is the skins first line of defense and can thicken with advancing age, disease, or exposure to sunlight, giving the skin a dull, thickened, “leathery” appearance, often with clogged pores and fine wrinkling. Exfoliation is the process of reducing excess non-living skin cells, which lets the natural beauty of the skin show through, unblock pores, and reduce the barrier function of the skin just enough to allow better penetration of topical preparations. Increased skin cell turnover stimulates collagen production, increases skin thickness and improves skin tone. Exfoliation can be chemical, mechanical, or a combination of both.
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can be as simple as a “buffy” pad, loofa, or scrub, which may be “low tech but effective when strong exfoliation is needed. On the delicate facial skin, however, Microdermabrasion is the treatment of choice, offering controlled, gentle exfoliation with stimulation of the skin. The process involves a vacuum tip drawing very fine crystals across the skin surface; it does not use any pressure to “sandblast” the skin. The vacuum not only moves the crystals, it stimulates blood flow and actually increases the thickness of the fine collagen fibers in the skin.
The advantage of microdermabrasion over other mechanical exfoliation methods is controllability stimulation without irritation. Microdermabrasion is a good way to “jump start” the exfoliation process in patients who have many clogged pores, thick, weathered skin, and is often performed at monthly or quarterly intervals for maintenance.
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is usually performed with Alpha hydroxyl Acids (AHA), which are mild organic acids derived from various sources such as sugar cane, milk, and fruit. The most commonly used are glycolic and lactic acids, which dissolve the lipid bonds that bind together non living skin cells in the outer layer of the skin (stratum conreum). AHA’s also help the living layers of the skin thicken and retain water, thereby “plumping” the skin and decreasing fine wrinkling. A thinner stratum corneum also means improved clarity of the skin, and better absorption of other topical agents, such as “bleaching: creams, retinolds, antioxidants, ect.
Low concentrations of AHA’s are available in a variety of consumer skin care products. Products with a higher concentration (more acidity) are more effective, and are available only from licensed practitioners.
High concentrations of AHA are the basis for light, or “lunchtime” peels, and are often combined with herbal or fruit extracts (“pumpkin peel”, “blueberry peel”, ect.). As the concentration of AHA increases, so does the incidence of side effects such as redness, irritation, blistering and peeling, and increases the likelihood of sun damage and discoloration in patients who do not use sunscreen.
A typical exfoliation regimen for a new patient would consist of daily home use of an alpha-hydroxy lotion for 2 weeks, followed by a light peel or microdermabrasion. Results can be achieved more quickly by utilizing a series of microdermabrasions and/or light peels performed every 2 weeks for a total of 4-6 treatments, with occasional “maintenance” treatments as needed, usually every 3 months.