Chemical Exfoliators: A Guide to Your Next (Skin) Acid Trip
To the uninitiated, acids on skin sound like a nefarious never, nope, not gonna — right up there with vampire facials (ouch). But before you pass them off and spray them away with holy water, remember how smooth and soft and glowing your skin is after exfoliation. Certain acids are making gains in the beauty mainstream as chemical exfoliators and they’re not as scary as they sound.
Plus, they work (in super small, teeny tiny doses).
One of the major benefits of chemical exfoliation instead of physical exfoliation? No scrubbing. Physical exfoliators use friction between the scrub and your skin to slough away dead cell buildup while chemical exfoliators that more closely match skin’s more acidic pH level dissolve the glue holding dead skin cells on skin’s surface so they can release. See? Less scary than you thought.
But before you start dropping just any ‘ole acid on your skin hoping for a radiance resurrection, make sure you brush up on which acids do what and when to use them.
A quick lesson on why they work: Our skin skews slightly acidic in its pH, so commonly, acidic skin-care ingredients are heavy-hitters in every aspect of our regimens from adding hydration (a la hyaluronic acid) to brightening (care of L-ascorbic acid). (1)
What Are AHAs and BHAs (and PHAs)?
Alpha hydroxy acids (AHAs) help dislodge dead skin cells without going deep into the pores, making them a good place to start or better suited to dry skin. Derived from plants parts like sugar, milk or fruit, they are water-soluble and best used at night since they can make skin more sensitive to the sun while they work. If you’re using AHAs, always wear your sunscreen. If you’re not using AHAs, always wear your sunscreen. (2)
Beta hydroxy acids (BHAs) also remove dead skin cell, but they go one step further by going deeper into pores. Because they’re oil-soluble and unclog pores, BHAs are a better choice for oily skin types. The most common BHA is salicylic acid, a popular ingredient in anti-acne products. It can work wonders, but — heads up! — it can also be drying. However, BHAs don’t have the same sun sensitivity effects as AHAs so you can use them day or night.
Polyhydroxy acids (PHAs) aren’t as popular or well-known, but still deserve an honorable mention for their mildness. Similar to AHAs, but even more gentle, they have a slower absorption rate, making them ideal for sensitive skin. (3, 4)
Your Complete Guide to AHAs
And everything you need to know about them
Derived from sugar cane
You’ve heard the word glycolic before and seen it splashed across countless products. Well here’s why: It’s a smaller size than other alpha hydroxy acids, making it more effective penetrating skin and less irritating. Even though it’s an AHA, glycolic acid good for all skin types, even oily because it does help unplug pores.
Derived from milk
Second in popularity only to glycolic acid, lactic acid works the same way to soften and loosen dead skin cells but its larger size penetrates more slowly for a gentler exfoliation. Other benefits unique to lactic acid? Strengthening the skin’s barrier lipids and increasing moisturization.
Derived from brown rice, beans, seeds and grains
Phytic acid works a bit differently by attracting and binding calcium which in turn weakens dead skin cells bond to safely release from skin’s surface. It also helps reduce hyperpigmentation and works at a lower pH without causing irritation, making phytic acid a win-win-win for sensitive skin.
Derived from mushrooms or sake
Yes, kojic acid is a byproduct of Japanese rice wine — specifically fungus during the fermentation process. And although it’s still more popular in its native Japan, kojic acid has earned its place in the AHA ranks for melanin-decreasing magic. It’s a less aggressive lightening treatment for those looking to fade spots or hyperpigmentation, but it can lead to inflammation and sensitivity so proceed with caution.
Derived from citrus fruits
Unlike its AHA cousins glycolic and lactic, citric acid is a pretty weak chemical exfoliant. However, it’s also super gentle and a great starter for the intrepid acid convert before graduating to the more serious glow-getters.
Derived from bitter almonds
Popular for rosacea and great for acne thanks to its antibacterial properties, this gentle AHA is known to exfoliate without brightening. Which, come to think of it, is actually win when you consider not everyone wants that super polished look — especially your skin’s brightness is already dial up to eleven.
Derived from apples
Malic acid delivers less punch than glycolic or lactic, but more than citric. Best used as a side-kick to other AHAs than as a superhero solo act, it can help adjust the pH of a product in the acidic skin-happy direction.
Derived from grapes and found in wine
This more obscure AHA is less stable and not as well researched as its more popular siblings. But it is an antioxidant gaining popularity as a pH balance. We’d file this under skin-things-to-keep-an-eye-on, but maybe don’t commit just yet.
The Only BHA You Really Need to Know
And a shout out to the only PHA you might want to know
Naturally occurs in plants like willow bark, wintergreen leaves and sweet birch
Salicylic is the go-to beta hydroxy acid that’s super effective as a heavy-duty exfoliant for (almost) everyone. Unlike AHAs that work mostly on the surface of the skin, salicylic acid breaks apart the attachments keeping dead skin cells hanging on and penetrates deeper, triggering exfoliation from the outside in. More than exfoliation, salicylic is acne’s enemy number one, but it can irritate dry or sensitive skin with overuse.
You're on PHA for today
Polyhydroxy acids don’t get much love, probably because they don’t penetrate as deeply as AHAs. One noteworthy exception? Gluconolactone has been lauded as an effective chemical exfoliator without the redness or sensitivity of heavier hitter.
Why You Should Never Overdo Exfoliation
Regular exfoliation can yield ten-fold benefits in the form of smoother, stronger, brighter and even better-moisturized skin. But it’s easy to overdo — and that’s when folks tend to run into issues of irritation, rawness, tightness and sensitivity, or just looking too shiny. There’s a fine line between rejuvenation and damage with chemical exfoliators. Start with a more mild AHA once or twice a week, then build from there. Ultimately, an alliance between your AHAs and BHA will provide the best results, but for some, an AHA-BHA combo just might be more than our skin can tolerate. Listen to your skin. Don’t force it into an acid relationship. And go slow.