Understanding how acid exfoliation changes the skin

by Deborah Duffey, Chief Product Development officer and President   July 9, 2021

If the idea of using acid on your skin scares you, you’re going to want to revisit that assumption. The acids we’re referring to here won’t burn or injure skin, in fact they’ll do the opposite—turning skin soft and smooth while it clears pores and prevents premature aging.

Acids in skincare are common because they are multifunctional and easy to incorporate into skin routines—it’s even possible you’ve used a product with one without realizing. And while they provide a variety of benefits for the skin, they excel because they do one specific thing very well: exfoliate.

What is acid exfoliation?

Just like you might use a scrub or rough cloth to physically clear skin of dead skin cells and turn your skin baby soft, you can use acid exfoliators in a similar way. But the way it works—and it’s benefits—go beyond what any rough scrub could provide.

There are several types of acids, each of which have their own specialities, but in general they all work by dissolving the connections between dead skin cells so they can be cleared away. Some types also penetrate pores to remove oil.

Acid exfoliation not only makes skin soft to the touch, but it also leads to increased skin cell turnover. Pigmentation clears more quickly than it would on its own, and fine lines and loss of firmness are prevented. Acids can clear acne and blackheads, and add a youthful glow.

Physical vs. Chemical Exfoliation

In the past, exfoliating skin meant rubbing it with a sugar scrub or a rough, textured mitt. This method is called physical exfoliation because you are using an item to physically rub dead skin cells from your face and body.

Acid exfoliation is a little different. Much like we might think of acid as eating through rust or burning through surfaces, the acids we use in skincare gently destroy excess oils and the connections between dead skin cells. While it sounds intimidating to use acids on your skin, it can actually be less irritating than physical exfoliation. This is because some scrubs, cloths, or similar exfoliating tools can create microtears in the skin, and overuse of these items can be too abrasive. Acids are used through various products—liquids, serums, peels, and more—and they exfoliate more evenly.

Physical exfoliation certainly has its place in a skincare routine, but be sure to choose gentle methods and use them lightly. But after integrating acid exfoliation into your life, you might find you no longer prefer other exfoliators!

Are acids safe for the skin?

The acids in skincare products have been specifically formulated to be safe for skin. There’s a wide range of types and strengths, so most everyone can safely use them. But the products you choose depends on your skin type and the skin concerns you want to target—more on this when we discuss specific acids.

If you have rosacea, some acids can aggravate the condition. But one type of acid, azelaic acid, is actually a treatment for rosacea, and it decreases inflammation and redness of the skin. Look for this when choosing an acid product, or speak with your dermatologist about a stronger, prescription strength formula.

And if you have extremely sensitive skin, look for acids specifically designed to be gentle. But be careful—if your skin’s sensitivity is the result of a damaged skin barrier, it may be worthwhile to let skin heal before adding acids to your routine. You’ll know this might be the case if your skin tends to be red, irritated, and reactive to skincare products.

What acids are used in skin care?

Acids are broken down into two main categories: BHA and AHA.

BHAs, or beta hydroxy acids, are oil-soluble, and have the ability to penetrate deep into pores to clean them out. This makes BHAs an especially good acid to use if you have acne-prone skin. In skincare, you’ll most often find them in the form of Salicylic Acid.

AHAs, or alpha hydroxy acids, are water-soluble. They don’t penetrate pores and clear oil like BHAs do, instead they work on the skin’s surface to exfoliate dead skin cells away. They also help fade discoloration and even skin tone. AHAs include glycolic, mandelic, citrus, lactic, malic acid, and others.

Acids with a larger molecule size don’t penetrate skin as deeply and can be better for sensitive skin. Lactic acid, for example, is a gentle exfoliant due to its size, while glycolic, as the smallest acid molecule, can be more intense.

Most acids are derived from plants or natural sources, including willow bark and sugar cane.

How are acids used in skin care?

Acids are used across a range of products. You’ll find them in masks, peels, cleansers, treatments, and even sprinkled into moisturizers and serums. The type of acid and its percentage will determine the strength of the product and what skin condition it is targeting.

Here’s a quick overview on a few of the most common types of acids.

Salicylic acid comes from willow tree bark and is a BHA, which makes it perfect to treat acne and clear clogged pores. It can reduce oil and inflammation. It’s most often found in cleansers, peels, and treatments, at a maximum concentration of 2% (professional products can have a higher percentage). While salicylic acid is recommended for acneic skin, other acids also have anti-acne benefits, too.

Glycolic acid is an AHA and comes from sugar cane. It’s one of the most popular acid options due to its small molecule size that allows it to penetrate skin deeply. Glycolic acid is your best bet when choosing an overall beneficial acid—it exfoliates to even skin tone and clear pores, smooths texture, stimulates collagen production, and reduces the look of fine lines and wrinkles. Look for concentrations of 5-10%, and start at the low end (or go slow) if you’re new to acids. A dermatologist or esthetician can provide peels that are up to 70% glycolic acid, which will provide major results but also requires downtime while skin heals.

Lactic acid is a gentle AHA derived from milk. It has a larger molecule which means it doesn’t penetrate skin as deeply, so while it doesn’t have the strength of glycolic it is still extremely effective. Lactic acid performs in the same way as glycolic but it stays at the surface level, leading to less irritation. It can be a beneficial acid for those with dry skin to use because it can draw moisture to the skin and boost hydration. Products with concentrations as low at 5% can fade discoloration, and at 8% it improves sun damage and texture.

Some other acids you might see include mandelic acid, azelaic acid, and ferulic acid. You’ll find combinations of acids in some skincare products that allow you to get the benefits of multiple types in one, but preformulated to be skin safe. Until you become more comfortable with acids, it’s best not to use different acid exfoliating products at the same time.

Acids are available in stronger concentrations through professionals. Chemical peels are treatments with high percentages of acids, and the strength and formulation can be customized based on your needs. While some require downtime (and will leave you red and peeling), once skin heals you’ll see fast results!

Not every ingredient with ‘acid’ in the name functions as an exfoliator. Hyaluronic acid and ascorbic acid are common ingredients, but they work very differently than salicylic or glycolic acid. Hyaluronic acid, for example, is a hydration booster (it’s also already present in your skin!). Ascorbic acid, better known as vitamin C, is an antioxidant that stimulates collagen production and evens skin tone.

How often can I use these products?

Many acid products can be used every day, but it’s best to start slow if you’re new to acid exfoliation or trying a new product. Because they can make the skin more sensitive to the sun, using them at night is usually recommended. When trying a new product, start using just a few times a week and monitor how your skin reacts. If you experience peeling, redness, or irritation, give your skin time to heal before using the product again. And be sure to add nourishing products into the rest of your routine to support your skin’s healing, like moisturizers and serums.

Over exfoliation can lead to skin problems on its own—more isn’t always better when it comes to acids. Even after your skin becomes accustomed to acid exfoliation, you may find that you see the most benefits when you keep usage to just a few times a week.

What if it stings or my skin turns red?

Depending on their strength, some discomfort or redness after applying acids is natural, especially if your skin isn’t used to them. Expect a flush and a light sting that subsides within a few minutes. Extreme burning or redness is not normal—discontinue the use of the product should this occur, and seek out a dermatologist to determine the cause (and treatment, should you need it!).

If your skin begins to show signs of irritation several days after you begin an acid product, this might be a sign that you need to cut back on how often you’re using it. Don’t begin again until your skin heals, and be sure to space out treatments to avoid irritating your skin again.

Is it safe for me to be in the sun?

Acids, specifically AHAs, can make skin more sensitive to the sun. BHAs like salicylic acid do not increase skin’s sensitivity to the sun. While it’s important to wear sunscreen every day regardless, be especially mindful of your sun protection if you incorporate acids into your routine.

Because AHAs make the skin more susceptible to sun damage, using acids without sunscreen can actually make the skin issues you’re targeting—like premature aging or discoloration—worse. But together, a routine that includes acids and sun protection can be a powerful combo for healthy skin.

How should I nourish skin if I'm using acids?

While acids have a lot of benefits, they can also strip skin of its protective layer and make skin vulnerable to irritation if they aren’t used correctly. One way to avoid this is to nourish skin with hydrating and soothing products. Don’t use too many exfoliating products in one skincare routine or at the same time (as explained in the next section), be sure to moisturize skin, and don’t forget your sunscreen.

It can also be helpful to find an acid product that works to reduce irritation without decreasing the benefits. For example, Kara Vita uses encapsulated anti-inflammatories to eliminate redness and irritation from the acid in the Glycol-X line of products.

Are there any ingredients I should avoid if I am using acids to exfoliate my skin?

Acids can be very powerful on their own, and because of this it’s best to be careful about the products you’re using during the rest of your routine. Until your skin is accustomed to acids and you’ve learned how your skin reacts, it’s best to err on the side of caution.

If you’re using a product that physically exfoliates your skin, like a scrub or a face tool, cut back or stop using it altogether. Too much exfoliation can irritate and damage skin. Over time, you can begin incorporating it back into your routine, but it’s never a good idea to use a scrub and an acid at the same time.

If you use a retinoid product, don’t use acids at the same time—use each product alone on different nights or, if the product allows it, use the acid treatment in the morning and the retinoid at night (if you spend a lot of time in the sun, avoid using AHAs in the morning). Both acids and retinoids exfoliate skin, so using both increases the chance of over exfoliation and irritation.

It’s also a good idea to not combine different acid products. Introduce one to your routine first, and after some time monitoring your skin, introduce the second product. Some people may find it beneficial to use salicylic acid, a BHA, in the morning and an AHA like glycolic acid in the evening. But remember not to overdo it and take it slow! Too much exfoliation can cause problems on its own.

With the right approach, acid exfoliation can improve skin texture and tone, clear acne and clogged pores, and smooth out fine lines. Just take it slow toavoid over exfoliation, and look for products that are gentle on skin. Welcome to the world of chemical exfoliation!