Toronto dermatologist Dr. Michelle Levy writes about common skin problems, controversies and developments, and provides science-based answers to common questions in our dermatology blog.
Chemical peels have long been used by dermatologists to improve the skin's appearance. There are several different types of chemical peels, and they are often classified based on their active ingredients. The following is a description of the most common types of peels and an explanation of what they can (and can not) accomplish.
What Are Chemical Peels?
Chemical peels involve the application of acidic (or less often, basic) solutions to the skin. They work by causing exfoliation of the top layer(s) of skin. In doing so, they remove some of the pigmentation and signs of sun damage and give the skin a "fresher" appearance. They can also unclog pores and (modestly) stimulate collagen production. There are several different types of peels, and their effectiveness and side effect profile depend on their ingredients, concentration, and, in some cases, the length of time that the peeling solution is left on the skin.
Chemical peels are usually classified by the depth of peeling they cause. Most peels done today are superficial or light chemical peels. These cause peeling in the top layer(s) of the skin (the stratum corneum and the epidermis) and sometimes in to the upper portion of the second layer (the dermis). Medium depth peels will cause peeling in both the upper and the deeper layers of the skin, while deep chemical peels will cause peeling into the deeper part of the dermis. Some medium depth peels and virtually all deep chemical peels have been replaced with laser treatments, which are more predictable and, in some cases, more effective.
Why Get A Chemical Peel?
Chemical peels are most frequently used to "freshen" the skin, as an anti-aging treatment, or to improve acne and/or skin discolouration.
The following skin concerns can be addressed to an extent with peels:
Photoaging (skin aging induced by sun exposure)
Hyperpigmentation (darkening of the skin)
Pre-cancerous skin growths (medium and deeper peels)
What Are Chemical Peels Not Used For?
Peels are generally not helpful for treating deeper wrinkles, especially those caused by facial expressions. They will also not improve most cases of acne scarring or more severe sun damage. Finally, peels do not treat facial redness or "broken" blood vessels; laser treatments are required to improve these.
What Are the Different Types of Chemical Peels?
1. Salicylic Acid Peels:
Salicylic acid is a beta hydroxy acid (BHA) which is often used for oily, acne-prone skin. It is used in low doses (up to 2%) in over-the-counter acne treatments. Salicylic acid peels in concentrations of 10-30% are done in doctors' offices. Because salicylic acid is oil-soluble, these peels penetrate into the pores of the skin and are good at unclogging blocked pores. Because of this they can be useful for treating acne. Those who have an allergy to aspirin must avoid this type of peel.
2. Glycolic Acid Peels:
Glycolic acid is an alpha hydroxy acid (AHA) which is naturally found in some fruits. It is the most widely used peeling agent and is available in strengths ranging from 20-70% (lesser percentages are used in over-the-counter products). It is often used for mild sun damage in order to "freshen" the skin, even out skin tone, or improve discolouration. Like salicylic acid, glycolic acid can also unclog pores and improve acne. The effects of this type of peel depend on the strength of the solution and on the length of time it is left on the skin. Glycolic acid must be neutralized, usually after 2-4 minutes, making it important to choose a practitioner who is experienced. If the acid is left on too long, side effects are more likely.
3. Trichloroacetic Acid Peels:
Trichloracetic acid (TCA) is a stronger peeling agent than glycolic acid or salicylic acid. 10-30% TCA peels are considered to be superficial peels while those that contain 35-50% TCA are considered to be medium depth peels. They are most often done for sun damage and can improve some fine lines and wrinkles. Medium depth TCA peels may take a week or so to heal (longer if done on areas other than the face).
4. Combination Peels:
Combination peels usually utilize two or more active ingredients. There are several commercially available proprietary peels that combine several peeling agents, sometimes including ingredients such as lactic acid, citric acid or mandelic acid. Jessner's solution is a specific type of combined peel that includes resorcinol, salicylic acid, lactic acid and ethanol. This solution is sometimes combined with TCA for medium depth peeling.
What Will I Look Like After a Chemical Peel?
Light peels may result in a mild pinking of the skin for 1-3 days, followed by mild skin peeling. In some cases, the peeling is so mild that it may not be noticeable or may only be appreciated as a subtle dryness of the skin. Medium depth peels may take 7-10 days to heal with more noticeable redness and peeling.
What are the Possible Side Effects of Chemical Peels?
While the vast majority of peels heal without any problems, peels can uncommonly cause side effects such as skin discolouration, infection, or rarely even scarring (among other problems). The risk of side effects is low for light peels but is higher for medium and deep peels. All peels should only be performed by qualified and well-trained individuals, and medium depth peels should only be done under the supervision of a dermatologist or plastic surgeon.
In order to minimize the risk of complications, you must carefully follow the post-peel instructions your doctor gives you. It is extremely important to protect your skin from the sun after any chemical peel. The skin will be more sensitive to burning, and sun exposure during this time can cause skin darkening (hyperpigmentation) which can be very slow to resolve. This is more common in people with darker skin types, who may want to avoid chemical peels in the summer unless they are confident they can religiously protect their skin from the sun while it heals.
When Can I Expect Results From a Chemical Peel?
In general, several chemical peel treatments are required in order to achieve a desired results. Expect 3-6 treatments, often 2-4 weeks apart. In many cases, maintenance treatments are needed in order to maintain the improvement.
What is the Difference Between a Chemical Peel and Microdermabrasion?
Microdermabrasion is another means of superficially exfoliating the skin. While chemical peels use chemical solutions to accomplish this, microdermabrasion uses uses fine crystals or tiny diamond chips with a vaccum that is run across the skin to remove the top layer of skin. In some cases, certain ingredients, such as salicylic acid or anti-oxidants, are added during the microdermabrasion procedure to boost its effectiveness.
Tips For Getting the Best Results From A Peel and Avoiding Complications:
If you are prone to cold sores, notify your doctor; they may suggest you take an antiviral medication prior to having a medium-depth peel. Avoid any treatments if you have an active cold sore.
Notify your doctor if you have taken isotretinoin (Accutane) within the past year, or if you have a history of abnormal scarring.
Do not peel, pick or rub at your skin after a peel.
You may need to stop some skin care products (such as vitamin A creams) before a chemical peel and then wait to re-start them until your skin has healed. Tell your practitioner which skin care products you are using.
Your skin will be more sensitive to the sun after a peel. Protect it with a broad-spectrum sunscreen with an SPF of 30 or higher. Not doing so may result in skin discolouration, particularly if the peel is performed in the summer.
Use a non-comedogenic moisturizer 2-3 times per day after a superficial chemical peel; this will help with some of the dryness the peeling solution causes.
Follow any other post-peel instructions your provider gives you closely.
Chemical peels remain a useful skin treatment that can offer a number of benefits. They should be performed by someone who is skilled and qualified, as poor technique can result in unwanted side effects. Done properly, they are a relatively inexpensive means of achieving improvement in early sun damage, evening out skin tone and treating acne.