AHA vs. BHA: How to Choose the Right Chemical Exfoliant

A fun skincare shopping trip can quickly turn into a nightmare as there's a plethora of different options - brands, formulas, and concentrations. This is especially true if you're looking for the right chemical exfoliant (AHA vs. BHA) for your skin concerns.

July 25, 2021 9 minutes read

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If you want a radiant complexion and clean and rejuvenated skin, exfoliation should certainly be a part of your skincare routine. Our skin naturally removes dead skin cells from its surface daily, but with age, this process slows down quite a bit, leaving the skin dull, wrinkly, and uneven. That's why it needs a little push from the outside in the form of different exfoliating products, helping it get rid of build-up dead skin cells and make way for soft and smooth skin hiding beneath.

But, when you think of exfoliating products, face scrubs are probably the first thing that comes to mind. However, old-fashioned harsh and gritty scrubs are now replaced by gentler (and more effective) exfoliating acids or chemical peels, most commonly AHAs (alpha hydroxy acids) and BHAs (beta hydroxy acids).

So, how do they work? What's the difference? And which one is better for your skin?

If you often find yourself wondering about these, you're at the right place. In this article, we'll try to answer all your burning questions about chemical exfoliants and their wonderful benefits for the skin.

AHAs and How They Work

AHAs, or alpha hydroxy acids, are water-soluble chemical exfoliants derived from sugar cane, fruits, or milk. They target both epidermis, the outer skin layer, and the dermis, the deeper layer. In the outer layer, AHAs exfoliate or remove dead skin cells from the skin's surface. To be more precise, they weaken the adhesions or bonds between these cells, allowing them to fall off more easily, thus exfoliating effect.

Additionally, AHAs increase collagen production in the dermis. They do this by stimulating fibroblasts - connective tissue cells that secrete collagen proteins, maintaining the structural framework in the skin.

Types of AHAs

There are seven most common types of AHAs that you'll likely find in skincare products. These include:

Glycolic acid

The most popular and widely used type of AHA is glycolic acid. It's derived from sugar cane, and thanks to its relatively small molecular size, it's one of the strongest AHAs. Glycolic acid is an all-purpose chemical exfoliant, targeting different skin concerns, such as anti-aging, acne, hyperpigmentation, dry skin, and others.

Lactic acid

Lactic acid is the second most used AHA, right after glycolic acid. It's made from milk lactose. Since it's much gentler than glycolic acid, lactic acid is a preferred choice for those with sensitive skin. It's also excellent for treating hyperpigmentation, age spots, uneven complexion, and large pores.

Mandelic acid

This AHA is derived from the almond extract. Since it contains larger molecules, mandelic acid is a mild exfoliant, usually used in combination with other AHAs. It's effective for treating hyperpigmentation, inflammatory acne, as well as improving pore size and skin texture.

Tartaric acid

Tartaric acid is perhaps the least known type of AHA, derived from grapes. Used alone, it may improve acne and sun damage. But it's most commonly combined with other AHAs to stabilize their PH levels.

Citric acid

This acid is derived from citrus fruits, just like the name suggests. Citric acid has weak exfoliating properties, but it's pretty effective in lowering the skin's PH levels, prepping it for other skincare steps in your routine. It's also a standard part of many skincare products since it has preservative properties.

Malic acid

This is a relatively weak AHA derived from apple acid. As a single ingredient, it doesn't do much for the skin. Therefore, it's often combined with other AHAs.

Phytic acid

Phytic acid is another mild AHA, derived from different grains and rice. It's widely used as an antioxidant rather than an exfoliant.

BHAs and How They Work

BHA is short for beta hydroxy acid, usually derived from tree bark and wintergreen leaves. BHAs work on the skin's surface, exfoliating it, as well as deeper inside the pores. Like AHAs, BHAs loosen the protein bonds between dead skin cells, making them easier to remove.

Moreover, they are fat- and oil-soluble, meaning that they are able to penetrate deep inside the pores. BHAs allow the oil to flow more freely inside the pores, preventing the build-up of dead skin cells that can clog the pores and stretch them out. They also possess photoprotective and anti-inflammatory properties.

Types of BHAs

In cosmetics, the most commonly used BHAs are the following:

Salicylic acid

This is the most common and strongest BHA that you'll see in skincare, derived from the bark of willow trees. Although salicylic acid is the strongest BHA, it's better tolerated and less irritating than glycolic acid, the strongest AHA, due to its larger molecule size. It's one of the most effective acne treatments, thanks to its anti-inflammatory properties and the ability to reduce oil production.

Willow bark extract

Also known as Salix Alba, willow bark extract has a high salicin content and is a natural alternative to salicylic acid. However, it's much weaker, and it won't provide you with the same results.

Betaine salicylate

Betaine salicylate is a combination of salicylic acid and betaine, a plant-derived amino acid with hydrating properties. This BHA has similar effects to salicylic acid, but it's much gentler to the skin.

Other BHAs include tropic acid and trethocanic acid, but these are rarely used in skincare.

The Shared Benefits of AHAs and BHAs

As both AHAs and BHAs have exfoliating properties, they have several shared benefits for the skin:

Improve Skin Texture

Both AHAs and BHAs are effective exfoliating agents, removing the surface layer of dead skin cells and leaving the skin smooth and soft.

Reduce Fine Lines and Wrinkles

AHAs, glycolic acid in particular, as well as salicylic acid in higher concentrations, have a stimulating effect on the collagen in the dermis, increasing its density. As a result, both acids can improve the appearance of fine lines and wrinkles and contribute to better firmness of the skin.

Improve Skin Tone

Both types of chemical exfoliants induce the shedding of dead skin cells, peeling away the surface layer of the skin (stratum corneum consisting of dead skin cells) and making way for new and evenly pigmented skin. Therefore, they fade dark spots and even out the overall skin tone.

Prevent Acne

By exfoliating the build-up of dead skin cells that can lead to clogged pores, both AHAs and BHAs prevent and reduce acne. They can also decrease skin inflammation, the main culprit for rosacea, acne, and other skin concerns.

Hydrate the skin

Both AHAs and BHAs act as humectant agents (AHAs more so than BHAs), helping the skin attract and hold onto moisture.

AHA vs. BHA: What's the Difference?

We could sum up the differences between AHAs and BHAs in this way:

BHAs Can Penetrate More Deeply

AHAs are water-soluble, while BHAs are oil-soluble. This means that AHAs have the biggest impact on the skin's surface. Once they exfoliate the upper layer of the skin, the epidermis, they can work a bit deeper into the dermis, stimulating collagen production. On the other hand, oil-soluble BHA can penetrate more deeply into the skin, working on the skin's surface and inside the hair follicles, exfoliating and reducing blemishes.

AHAs Are More Irritating

Generally, if you use any exfoliating agent too frequently, you'll irritate your skin and possibly worsen its condition. However, due to their smaller molecular size and often higher concentrations, AHAs (particularly glycolic acid) are more associated with skin irritation and redness than BHAs.

BHAs Are Better for Tackling Acne

Besides scraping off dead skin cells from the skin's surface, BHAs can also work their magic deeper inside your pores. Because they are oil-soluble, they can do a deep cleansing of your skin, unclogging the pores and reducing oil production. Therefore, they are better suited for treating acne, blackheads, and whiteheads, as well as preventing the new ones from forming.

AHAs Are More Effective for Reducing Surface Wrinkles

AHAs may stimulate collagen synthesis and the production of hyaluronic acid inside the dermis. For this reason, they are more effective in improving the hydration and plumpness of the skin. As a result, regular use of AHAs can lead to even skin tone, minimized fine lines and surface wrinkles, and better hydrated and less patchy dry skin.

AHAs Increase Skin Photosensitivity

Unlike BHAs that can even protect the skin from UV radiation, AHAs increase the skin's sensitivity to sunlight. Therefore, you should use your AHAs with caution and always wear sunscreen to protect your skin from sun damage and premature aging.

So, Which Acid Should You Choose - AHA, BHA, or Both?

Now when we have covered the basics and understand better how AHAs and BHAs work, the question remains - Which acid should you go for?

Well, it will all depend on your skin type and the concerns you want to target. So, here are our final tips:

Use AHAs If:

You have dry skin: AHAs act as humectants and will help dry skin hold onto moisture. Mild concentrations of lactic acid will best serve this purpose, as it has fantastic moisturizing properties;

You have wrinkles: Glycolic acid, as well as lactic acid, stimulates collagen production and increases the thickness of the dermis. Therefore, these are your best bet for fighting the signs of aging. For best results, opt for glycolic or lactic acid of at least 8% strength, but be aware that these can make your skin more vulnerable to sun damage. So wear your sunscreen generously and diligently throughout the day;

You have mild hyperpigmentation and scars: For surface-level marks and scars from past acne, regular sloughing off dead skin cells can do wonders. For this purpose, you could use AHAs that are weaker and gentler to the skin, such as lower concentrations of mandelic or lactic acid.

How to Use AHAs?

While AHAs are safe for any skin type, you should be mindful if you have extremely dry or sensitive skin. If that's the case, start with skincare products that contain a low concentration of your chosen AHA and gradually work your way up.

It's also essential not to over-exfoliate your skin as this can exacerbate your skin condition and irritation. Therefore, if you're only starting with your exfoliating routine, do it only once a week in the beginning and give your skin a chance to get used to it. Once you feel your skin can handle more frequent application, increase it to twice a week, and then three times.

Additionally, all AHA types provide significant exfoliation and, thus, more sensitivity to the sun. Therefore, use them as part of your nighttime skincare routine, and don't skip on your broad-spectrum sunscreen during the day, regardless of the season.

Use BHAs If:

You have oily or combination skin: People with oily skin can greatly benefit from using BHAs because they can control oil production and reduce the shine significantly. However, it may take some time and experimenting before finding the right type and dose of BHA for your skin needs. Salicylic acid and betaine salicylate should both do the trick just fine;

You have acne: Salicylic acid is a go-to acid for fighting both open and closed comedones. You can start with a 2% salicylic acid for best results. It's highly effective in reducing the existing impurities and preventing them in the long run as well;

You want to remedy sun damage: Salicylic acid has photoprotective effects, as it can remove UVB-induced skin damage.

How to Use BHAs?

Since BHAs are much gentler to the skin, they are safe to use daily. However, you should still give your skin a chance to get accustomed to it first and use your BHA only a couple of times per week in the beginning.

Likewise, compared to AHAs, BHAs won't make your skin as sensitive to the sun. However, you should still wear your sun protection daily to prevent any sun damage.

Can You Use AHA and BHA Together?

If your skin needs and can tolerate it, you can use both AHAs and BHAs. However, with many shared benefits of both types of exfoliating acids, there's rarely a need to do so.

Nevertheless, if your skin needs a more thorough exfoliation or you have stubborn acne, advanced signs of sun damage, deep wrinkles, uneven skin tone, and extremely dull complexion, you could try using both and experiment until you find the winning combination.

How to Use Both AHA and BHA?

Unless one product contains both acids, there's no need for you to layer them on top of each other. Instead, it's best to use one in the evening and the other during your morning skincare routine. Also, you could use them on alternating days. This way, you'll decrease the risk of skin irritation, purging, and other side effects of over-exfoliation.

Another way to combine them is to use them both simultaneously but on different parts of your face. So, if you have combination skin and oily T-zone, apply your BHA to that area and your AHA to the other drier parts of your face.

Some Parting Words of Advice...

Both AHAs and BHAs yield some great exfoliating benefits to the skin. And while each ingredient shares a number of similar perks, they are targeted at different skin goals.

All in all, if you're looking for an all-purpose treatment and you want your acid to give you a boost of extra hydration and some anti-aging properties, opting for an AHA would be your best bet. On the other hand, if you're battling a constantly shiny complexion and persistent acne, give a BHA a try.

But, whatever you choose, make sure to start slow and use lower concentrations only once or twice a week. Then, once your skin gets accustomed to the new routine, you can gradually increase the frequency of application as well as the strength of the acid.

FAQs

Are BHAs stronger than AHAs?

BHAs are much gentler to the skin than AHAs, and they are usually safe to use daily. However, you should still give your skin a chance to get accustomed to it first and use your BHA only a couple of times per week in the beginning.

Is salicylic acid an AHA or BHA?

Salicylic acid is the most common and strongest BHA that you'll see in skincare. It's derived from the bark of willow trees. Although salicylic acid is the strongest BHA, it's better tolerated and less irritating than glycolic acid, the strongest AHA, due to its larger molecule size.

Can I use both AHA and BHA?

If your skin needs and can tolerate it, you can use both AHAs and BHAs. So, if your skin needs a more thorough exfoliation or you have stubborn acne, advanced signs of sun damage, deep wrinkles, uneven skin tone, and extremely dull complexion, you could try using both, AHA and BHA, and experiment until your find your winning combination.

Are AHAs or BHAs better for acne?

AHAs are water-soluble, while BHAs are oil-soluble. This means that AHAs have the biggest impact on the skin's surface. While BHAs can penetrate more deeply into the skin, working inside your pores, exfoliating and and cleansing them. Therefore, for acne-prone skin, it would be best to use a BHA, such as salicylic acid.

Is hyaluronic acid a BHA or AHA?

Hyaluronic acid isn't a BHA nor AHA. Although hyaluronic acid does have the word 'acid' in its name, it doesn't mean it has an exfoliating effect like AHAs or BHAs. Instead, hyaluronic acid acts as a strong humectant, hydrating and nourishing your skin.

Can I use AHA BHA every day?

AHAs tend to be irritating to the skin, so it's not recommended to use it every day, but rather 3 times a week maximum. BHAs, on the other hand, are much gentler to the skin, and if you have oily, acne-prone skin, you might benefit from the daily application of a BHA, like salicylic acid. However, if you're just starting with your exfoliating routine, choose BHA (or AHA) with lower concentration, and apply it only once a week in the beginning to avoid irritation.

Is salicylic acid the only BHA?

Technically, salicylic acid is the only BHA, and the most common ingredient found in skincare. However, there are other salicylic acid derivatives, like willow bark extract, also known as Salix Alba, which is a natural alternative to salicylic acid. Betaine salicylate, a combination of salicylic acid and betaine, is another BHA with similar effects to salicylic acid, but it's much gentler to the skin. Other BHAs include tropic acid and trethocanic acid, but these are rarely used in skincare.

Can I use Vitamin C serum after AHA BHA peel?

It's not recommended to use vitamin C serum after AHAs or BHAs. Vitamin C is an acid, ascorbic acid, and highly unstable one. Mixing it with other acids, such as AHAs (glycolic or lactic acid) or BHAs (salicylic acid), will render it ineffective. The only thing you can get from this combination is more irritation and worsening of your skin concerns.

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