What is Chemical Exfoliation?
Okay, so you’ve found a cleanser, moisturizer, and sunscreen for your perfect skincare routine, but what’s all of this hullabaloo about chemical exfoliants that skincare addicts are so obsessed with? Chemical exfoliation and, its skincare stepsister, physical exfoliation are methods of removing the outermost layers of dead skin cells to even the skin’s tone and texture. Chemical exfoliation has the added bonus of being able to evenly remove that layer of dead skin, unlike physical exfoliation, which unevenly removes this layer and risks the chance of irritation and inflammation.
Picture this – you’re trying to remove some ugly wallpaper in an old house so you can put on a fresh coat of paint (yes, you have to remove the wallpaper first!). You can either:
A) Painstakingly peel and scrape off the wallpaper bit-by-bit until most of it is removed.
B) Apply a solvent all over the wall that slowly dissolves the wallpaper glue so that it peels off in one sheet.
C) Screw this and hire a contractor!
Option A will take some of the drywall with it and leave a good amount of that tacky wallpaper on the wall. Option C will cost you a pretty penny and the contractors might not do a great job. However, Option B is easy for you, gentle on the walls, and saves money and time! Applying an even coating of glue solvent to that ugly wallpaper is the skincare equivalent of chemical exfoliation. (Hint: Option A = physical exfoliation; Option C = paying for an in-office specialist).
You can read more about physical exfoliation in Sam’s article to weigh the pros and cons of each method. Both are perfectly fine to use in a skincare routine, but in a head-to-head competition, the chemical option is often the most gentle and suitable for all skin types. The wide range of active ingredients available in chemical exfoliant products means that there is a chemical exfoliant suitable for nearly every skin type. If you’ve ever noticed sensitivity from using your Clarisonic too much or made a breakout worse by scrubbing your skin raw with St. Ives Apricot Scrub, chemical exfoliation is the answer you’ve been searching for!
Types of Chemical Exfoliants
The active ingredients in chemical exfoliants fall into three major categories – alpha hydroxy acids (AHAs), salicylic acid (SA), and polyhydroxy acids (PHAs). Where are beta hydroxy acids (BHAs), you ask? Although SA is routinely called a BHA, it’s actually a misnomer. More on that below.
The formulations of chemical exfoliants vary but are most often found as facial wipes, serums, or lotions. Typically, chemical exfoliants are meant to be used as a leave-on product, but it’s always important to read the product packaging for application directions! Some exfoliants will tell you to rinse them off after a few minutes.
Alpha Hydroxy Acids (AHAs)
AHAs are commonly used in skincare products for their keratolytic properties. The buildup of dead skin cells on the skin’s surface (hyperkeratosis) can cause your skin to look dull, increase the appearance of fine lines, and make flaky patches of dry skin show up under makeup and sunscreen.
AHAs are able to break up or “unglue” the cellular bonds that hold those dead skin cells together. To work this magic, they have to be formulated at a lower pH than our skin’s barrier. Effective AHA products should ideally be formulated around 4.0 or below, and anything above a pH of 4.5 may be completely ineffective at exfoliating or offering any of the typical AHA benefits.
Ingredients: The most common AHA ingredients include glycolic acid, lactic acid, and mandelic acid. Most AHAs are derived from fruits and other foods, so you may see them advertised as “fruit acids” on product packaging – glycolic acid comes from sugar cane, lactic acid from milk, mandelic acid from bitter almonds, and citric acid from various citrus fruits. If you see that buzzword on a product there’s a good chance it contains an AHA! AHAs are commonly found in concentrations of 5-15% and can be used daily in routines for all skin types.
Benefits: AHAs win the gold medal for eliminating dead skin buildup. They are also widely available and tolerated by all skin types. Glycolic acid is a classic when it comes to exfoliation ingredients and with regular use can tackle early signs of aging, hyperpigmentation, and acne. Lactic acid is a more gentle option that offers similar benefits, but it’s larger molecular size means that it penetrates the skin more slowly. Even larger, is the mandelic acid molecule, which makes it more tolerable on sensitive skin or those suffering from acne.
As if all of that exfoliating action wasn’t enough, AHAs also function as mild humectants. The regular use of topical AHAs can increase the skin’s hydration, which results in plump skin with reduced fine lines and dryness! (Excuse my enthusiasm — I just don’t think it gets better than that.)
Drawbacks: Introducing any new exfoliant to your skincare routine can result in mild tingling or stinging with the first few applications. This side effect is totally normal and can be reduced by adding the exfoliant in very slowly to your routine for a few weeks. If the stinging persists or isn’t tolerable after that adjustment phase, you may need to try a more gentle AHA (like lactic or mandelic acids) or try an even milder option like a PHA.
AHA Product Recommendations
|Paula’s Choice Skin Perfecting 8% Gel||Glycolic||8%||Low-strength glycolic is good for beginners; pump top bottle reduces the product’s exposure to light and air|
|Alpha Hydrox Oil-Free Treatment||Glycolic||10%||Available locally in stores; smaller product packaging which means fresh product since you’re replacing more often|
|MUAC’s 10% Mandelic Acid Serum||Mandelic||10%||Dark glass bottle & dropper top means the acids are well-protected with this packaging; can be drying due to alcohol content|
|Alpha Hydrox 14% AHA Swipes||Glycolic||14%||Swipes make application easy; high-strength glycolic may sting if you’re not adjusted to chemical exfoliants|
Salicylic Acid (SA)
Salicylic acid is endlessly and incorrectly referred to as a beta hydroxy acid (BHA). The BHA name-calling is a misnomer because salicylic acid does not have the same molecular structure as a true BHA. A true BHA should have a neutral hydroxyl group hanging around at a certain location; however, the properties of salicylic acid make that hydroxyl group acidic. True BHAs (those that are only BHA and nothing else) aren’t even used in skincare products. The only half-BHA products you’ll find are ingredients that can be classified as both an AHA and a BHA, like malic acid and citric acid. Even then, malic acid is relatively uncommon and citric acid is mainly used to adjust a product’s pH.
For daily use, SA should be concentrated at 2% or lower (0.5% and 1% are also available). Above 2%, you’re looking at a product that should be rinsed off after a few minutes and at or above 12-15% SA, it would be considered a chemical peel. It’s pretty powerful at low concentrations, so don’t feel like it’s “less effective” than that 10% glycolic lotion — they just serve different purposes!
Nearly every product with “BHA” on the label will have salicylic acid as an ingredient. Don’t worry — calling it BHA isn’t some scammy marketing tactic, it has just become the most common nickname for salicylic acid products. I mean…salicylic is a confusing word to read and pronounce when you see it on a product label.
P.S. It’s sa-luh-sil-ik.
Benefits: Unlike water-soluble AHAs, the quasi-BHA properties of SA make this ingredient oil-soluble and great for oily and acne-prone skin. Salicylic acid offers mild keratolytic and anti-inflammatory properties as well, but are more popularly known for their oil-fighting abilities. Regular use of salicylic acid will break up clogged pores, eliminate excess facial oil, prevent acne breakouts, and fight overall inflammation.
Drawbacks: While great at controlling oil, salicylic acid can be very drying. Overuse can lead to dry, flaky skin and irritation. Many people prefer to use BHA every other day instead of daily. Those with dry skin should proceed with caution when using salicylic acid products.
SA Product Recommendations
|Stridex Daily Care Acne Pads Maximum Strength||Salicylic||2%||Cheap and effective; a classic beginner product for an acne-fighting routine|
|Paula’s Choice Skin Perfecting 2% BHA Liquid||Salicylic||2%||More gentle and less drying than the Stridex; another good beginner choice|
|[re]fresh Salicylic Acid 2% Peel||Salicylic||2%||The name says “peel” but this product can be used daily; instructions say to rinse off with water after a few minutes|
|Paula’s Choice Skin Perfecting 1% BHA Lotion||Salicylic||1%||Lotion formula plus the 1% concentration makes this suitable for those prone to dryness|
|Avène Cleanance K Cream-Gel||Glycolic, Lactic, Salicylic||6% (GA), 2% (LA), 1% (SA)||Includes AHAs and salicylic acid to boost the exfoliating action and tackle multiple skin concerns|
Polyhydroxy Acids (PHA)
PHAs are relatively new to the skincare market and harder to find on the shelves at your local pharmacy (in fact, it’s probably impossible to find them outside of an online shopping cart unless you’re buying them from your dermatologist’s office). The most common PHA ingredients are gluconolactone and lactobionic acid. Gluco…, lacto…, what?? Names for PHAs are so crazy they don’t even have good abbreviations! PHAs do have big names but they also have big molecular structures. The large molecular structure of PHAs means that they don’t penetrate the skin as quickly as other chemical exfoliants and may be more gentle than AHAs.
Benefits: PHAs are a good option for those with dry or sensitive skin. Gluconolactone is the most prevalent PHA on the market and has similar effects of AHAs. It also claims to have added antioxidant and anti-inflammatory effects.
Drawbacks: PHAs are hard to find and more expensive than their more common AHA and SA counterparts. Some PHAs, while possibly beneficial, are patented and only found in a select few products. There’s also not as much independent research produced on their effectiveness, and it’s hard to determine just how effective they are when compared to cheaper and more popular AHAs.
PHA Product Recommendations
|Biologique Recherche Lotion P50||Gluconolactone, Glycolic, Lacitc, Malic||unknown||Cult classic; must purchase through retailers that require you to have an account to receive a price quote|
|NeoStrata Bionic Face Cream||Gluconolactone, Lactobionic||8% Gluconolactone, 4% Lactobionic||Typically if you see “lactobionic” in the ingredients list, it’s a NeoStrata product|
|NeoStrata Exuviance Ultra Restorative Creme||Lactobionic||10%||The entire NeoStrata Exuviance line includes PHAs|
Safely Adding Chemical Exfoliation to Your Routine
Signs of Over-Exfoliation & Irritation
If you don’t introduce chemical exfoliants slowly enough your perfect skincare routine could backfire. Just like with any new product, you should patch test and introduce exfoliants slowly. When adding an exfoliant, start with the lowest concentration available and work your way up.
Additionally, if you’re using things like spot treatments, clay masks, or forms of physical exfoliation you need to keep an eye out for signs of irritation. Increased redness, sensitivity, dry skin, or inflammation are all signs to back off of your chemical exfoliant (or other treatments) until your skin calms down.
In general, hydroxy acids increase the skin’s sensitivity to the sun. This means that when you’re using chemical exfoliants, during daylight hours you absolutely need to wear a sunscreen with at least an SPF 30 or greater. By eliminating that top layer of dead skin they also expose newer tissue to UV rays and increase your risk of burning and accumulating sun damage. So if you’re using your precious AHA serum to reduce freckles and fine lines, it won’t do you any favors without a proper sunscreen.
The exception to this rule is salicylic acid, which has not been shown to increase photosensitivity. In some cases, SA produces photoprotective effects in the skin (though, this still doesn’t replace a good sunscreen!)
Using Different Chemical Exfoliants Together
Different exfoliants can be used at the same time if your skin is adjusted to and tolerant of the actives in each formula. For example, someone with oily skin and hyperpigmentation (from acne marks or “scars”) might want to use salicylic acid to fight oil production and glycolic acid to reduce pigmentation. It’s perfectly fine to use one in the morning and one at night, use both at night, or alternate days between the application of each type. Just remember to check for signs of irritation and don’t overdo the exfoliation.
Lastly, be very careful when using chemical exfoliants with other topicals prescribed by your doctor. Prescription ingredients are often more powerful and sensitizing than products you can buy at the store. Rx topicals may increase your sensitivity to active ingredients like AHAs and salicylic acid. Check with your doctor before adding a chemical exfoliant to a prescription routine.
Quick Guide to Chemical Exfoliants
|Alpha Hydroxy Acid (AHA)||Remove excess dead skin to reveal a brighter complexion.||Glycolic, Lactic, Mandelic||Anti-aging; anti-acne; fights hyperpigmentation; mild humectant properties to increase moisture in the skin||Can sting at higher strengths; increases photosensitivity|
|Salicylic Acid (SA)||Oil-soluble acid that can unclog pores and prevent breakouts.||Salicylic||Acne-fighting; unclogs pores; eliminates excess facial oil; mild anti-inflammatory||Can lead to dryness with overuse|
|Polyhydroxy Acid (PHA)||Remove excess dead skin to reveal a brighter complexion.||Gluconolactone, Lactobionic||Typically more gentle than AHAs with similar benefits||Typically more expensive and hard to find|