Exfoliating Acids Explained: Everything You Need to Know

AHAs and BHAs, salicylic acid, and glycolic acids. You’ve heard of them, but all these terms can sound the same to those who aren’t familiar with the world of exfoliating acids. That’s what this guide is for.

These acids are what we call chemical exfoliants, and they’re often claimed to be the best form of exfoliation. In a nutshell, chemical exfoliation works by using compounds that can penetrate deep into the skin, unclogging the dirt within the pores, and sloughing off dead skin cells.

What are exfoliating acids?

Exfoliating acids are molecular compounds that work on the surface as well as deep within the skin to treat acne, acne scars, blackheads, whiteheads, inflammation, pigmentation, uneven skin tone, and irritation.

Chemical exfoliation is sometimes recommended over physical exfoliants like a scrub or peel-off product, because they’re able to get to the root cause of problems like acne, blackheads, and whiteheads without being unnecessarily harsh on the surface of the skin.

When we talk about exfoliating acid, that’s where different types come in. We have AHAs and BHAs, but there are also PHAs. Some forms of AHAs such as glycolic, lactic, and malic acid are found in skincare products whose main purpose isn’t necessarily exfoliation, and the same goes for salicylic acid. 

Where Can I Find Exfoliating Acids?

Some products that have alpha hydroxy acids and even a beta hydroxy acid in their formula include cleansers, toners, overnight masks, undereye creams, and moisturizers. Their use and effectiveness in getting rid of dead skin and aiding cell renewal can also vary from skin type to skin type, with some conditions favoring a certain acid over another.

How do we know which are right for us, which work hand in hand, and how do we start incorporating them into our skincare routine? Let’s take a look at them one by one.

What acids exfoliate skin?

1. Alpha Hydroxy Acids (AHAs) – Glycolic Acid, Lactic Acid, etc.

AHAs are a chemical compound commonly used in the cosmetics industry. Their effects on our skin’s deeper layer, the dermis, are pretty great. For one, they’re shown to have visible effects on the process of keratinization as well as collagen production. 

Some examples of popular AHAs you may know are glycolic and lactic acid, citric acid, tartaric acid, mandelic acid, and malic acid. These are also acids you can find in food. Glycolic acid is a compound of sugarcane, lactic acid in milk, and citric acid in citrus fruits. Some formulations combine natural components, like willow bark extract.

Products containing an AHA or two often use a low concentration. This is why you’ll find most products, including the popular Paula’s Choice 8% AHA Gel Exfoliant product, have concentrations of no more than 10%. This low concentration makes these products suitable for regular use, as some studies show the use of an AHA exfoliant to increase photosensitivity. This is why you’ll also hear skincare gurus absolutely require daily use of sunscreen, especially after using an exfoliating product.

Glycolic acid, lactic acid, and citric acid have all been shown to have positive effects on photodamaged skin, a.k.a. skin that has incurred signs of sun damage. In biopsies, AHAs have been shown to increase the thickness of skin without any sign of inflammation.

AHAs work by reducing adhesion within skin cells in the epidermis, triggering exfoliation. On a surface level, they have a significant effect on the keratinization in the stratum corneum.

2. Beta Hydroxy Acids/BHAs – Salicylic Acid

We say “acids” — plural — but BHA usually refers to one thing: salicylic acid, one of the most effective forms of acne treatments. You’ll find over-the-counter products can have a concentration of salicylic acid of anywhere from 0.5% to 10%. 

Much like AHAs, salicylic acid can unclog pores from deep within and decrease inflammation especially in problematic skin conditions such as rosacea and acne. They both also remove surface wrinkles, even out skin tones, and remove dead skin cells. These common effects have birthed combination products, such as the Alpha Beta Ultra Gentle Daily Peel product from the Dr. Dennis Gross Skincare shop.

But where do BHAs differ from AHAs? According to INCIdecoder, AHAs as an overall product are stronger in certain ways but cannot go deeper into the pores in our skin barrier because they’re water soluble. On the other hand, lipid-soluble BHA is often used for speeding up skin cell turnover because it can go directly into the pores and slough off dirt and dust from there.

This is why salicylic acid is also considered better for treating blackheads and whiteheads than treating acne. However, combining it with the gold standard for acne treatments, benzoyl peroxide, can create an excellent all-around treatment for acne-prone skin types, oily skin, and pigmentation.

3. Polyhydroxy Acids/PHAs

Lastly, you have the polyhydroxy acids or PHAs. The upside: these molecules, including lactobionic acid and gluconolactone, are larger than AHAs or BHAs. This makes them less irritating, ideal for sensitive skin types. However, since smaller molecules have higher bioavailability, larger-sized PHAs can’t go deeper into the skin barrier. They do, though, have well-documented moisturizing and antioxidant properties.

How Do You Use Exfoliating Acid?

Skincare enthusiasts will cite a golden rule when it comes to exfoliating acids: slow and steady wins the race.

This is why first-timers are recommended to go no more than twice a week in their beginning stages of use. For any product that has actives, it’s also important to patch test. 

Exfoliating acid can come in many forms. There are bottles of concentrated exfoliants used specifically for that purpose, cleansers that have AHA or BHA compounds, moisturizers, toners, and so on. There are also chemical peels that combine different AHAs, BHAs, and PHAs for a more potent solution.

For most products, the standard is to start by applying them twice a week for two weeks. During this period, you can slowly introduce the actives into your skincare routine without irritating it. You can also observe how your skin reacts. Does it break out, feel smoother, have smaller pores, or stay the same? Keep an eye out for the side effects.

It’s also important to wear sunscreen every single day, especially when you apply your chemical exfoliant in the morning. On that note, most skincare specialists recommend applying these products at night to lessen sun exposure while your skin is still photosensitive from the acids.

Once you’re certain your skin can handle a higher dose, you can start using your exfoliating products thrice a week for two weeks. Gradually build up the frequency if you notice positive results.

Which Acid is Best for Exfoliation?

Dry and Sensitive Skin

One downside to these exfoliants is dryness. But that doesn’t mean you can’t find a way to add them into your regimen. Milder AHAs like glycolic and lactic acid, which also have moisturizing properties, can be great for dry and sensitive skin. Be sure to slather your sunscreen and wear it religiously to avoid sun damage.

BHAs and PHAs are great if your skin is looking a little dull, too. PHAs, especially, are moisturizing and have wonderful calming effects for those who have rosacea or eczema.

Oily or Acne-prone Skin

Those with oily skin or acne prone skin can try using a BHA to spot treat problem areas, especially those with blackheads, whiteheads, or pimples. They may also try a chemical peel which combines different acids as a once-a-week exfoliant.

Mature or Aging Skin

Alpha hydroxy acids have been well-known to fight off signs of aging, specifically wrinkles and fine lines. They do so by promoting collagen production in the epidermis, which gives way to the appearance of firmer and plumper skin. AHAs are also perfect for those who have hyperpigmented skin.

Skin with Ingrown Hairs

There are plenty of products that target ingrown hairs on the face, and surprise, they usually contain some lactic acid (an AHA) or BHAs. This is because these acids can lift dead skin, which can include the ingrown hairs.

What Acids Should Not Be Used Together?

You might have heard that incorporating a chemical exfoliant into an existing skin care routine can be tricky. What if my Vitamin C and AHA solution don’t get along? Which products can gel with my new BHA mask and which one might cause terrible problems?

To make this process easier, here are the skincare ingredients you should NOT be layering on top of your AHAs/BHAs/PHAs. You may use them at opposite times in the day or simply skip them altogether. They include:

Retinol

Retinol is great as an anti-aging ingredient and can even fight off sun damage. Sounds like an AHA, doesn’t it? But layering these two together can cause serious dryness. Don’t do this if you’re one of the people who has sensitive or dry skin.

Vitamin C

Vitamin C is an incredible ingredient with multiple benefits. It can achieve all of these wonderful effects — brightening, moisturizing, evening out skin tone — without being too harsh or stripping, because it’s quite low on the pH scale. This means Vitamin C is low on the acidic scale. 

When you add an alpha hydroxy acid, such as glycolic acid, into the mix, you’re altering the pH level of vitamin C. Technically, this is a safe combination, but you’re reducing the effectiveness of your vitamin C product when you do so. To get the most out of both products, your alpha hydroxy acid or BHA and vitamin C are best used at different times of the day.

Final Note

If you think there’s something missing in your skincare routine but you can’t quite put your finger on it, why not try chemical exfoliators? The result is clear across the board: you get clearer skin, reduce signs of aging, and can reduce anything from inflammation to hyperpigmentation.

We hope this guide was helpful in your skin care journey! Don’t forget to leave a comment and tell us what you want to read next!

Joey Baldonado

Joey is an AB Psychology graduate of the University of St. La Salle – Bacolod. Her life’s passions include writing, film, and spending hours on end binge-watching fashion vloggers on Youtube.