AHA vs BHA: Differences, Benefits & Which One to Use

Chemical exfoliants are commonly used in skincare to remove dead skin cells, improve skin texture and address concerns such as dullness, clogged pores and uneven skin tone. Two of the most widely used types are alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs).

Although both help exfoliate the skin, they work differently. AHAs are water-soluble and mainly target the skin's surface, while BHAs are oil-soluble and can enter oil-filled pores. This difference makes AHAs useful for concerns such as rough texture and uneven tone, while BHAs are commonly used for blackheads, clogged pores and acne-prone skin.

Understanding the difference between AHA vs BHA can help you choose an exfoliating ingredient based on your skin concerns, rather than simply following skincare trends.

What Are AHAs and BHAs?

AHAs and BHAs are groups of chemical exfoliants used in skincare products such as cleansers, toners, serums, moisturisers and chemical peels. They help loosen the buildup of dead skin cells, supporting smoother-looking skin and improving texture.

What Are Alpha Hydroxy Acids (AHAs)?

Alpha hydroxy acids, commonly known as AHAs, are water-soluble acids that primarily exfoliate the outer surface of the skin. They help loosen the bonds between dead skin cells, allowing them to shed more easily.

Common types of AHAs include:

• Glycolic acid: Has a relatively small molecular size and is commonly used to improve rough texture, dullness and the appearance of uneven skin tone.
• Lactic acid: Offers surface exfoliation and can also help attract moisture, making it a popular option in products for dry-feeling skin.
• Mandelic acid: Has a larger molecular size than glycolic acid and is often used in formulations intended for gentler exfoliation.
• Citric acid: Used in some skincare products for exfoliation and formulation-related purposes.

AHAs are commonly included in products intended to improve dullness, uneven texture, superficial pigmentation and the appearance of fine lines.

What Are Beta Hydroxy Acids (BHAs)?

Beta hydroxy acids, or BHAs, are oil-soluble exfoliating acids. The most commonly used BHA in skincare is salicylic acid.

Because salicylic acid is oil-soluble, it can work within oil-filled pores and help loosen the buildup of sebum and dead skin cells. This makes it particularly useful in skincare products for oily and acne-prone skin.

Common BHA ingredients include:

• Salicylic acid: The most widely used BHA in skincare, commonly included in products for blackheads, clogged pores and acne-prone skin.
• Beta hydroxybutanoic acid: Another compound classified among BHAs.
• Tropic acid: A less commonly used beta hydroxy acid.
• Trethocanic acid: Another BHA listed in cosmetic ingredient references.

Salicylic acid is the main BHA most consumers will encounter in everyday skincare products.

How Are AHAs and BHAs Different?

The main difference between AHAs and BHAs is their solubility and where they primarily work on the skin.

AHAs are water-soluble and mainly exfoliate the skin's surface. BHAs are oil-soluble and can work within pores where sebum and dead skin cells accumulate.

Neither acid is universally better. The choice depends on your skin concern, the product's concentration and formulation, and how well your skin tolerates it.

What Are the Benefits of AHAs?

AHAs are mainly used to improve the appearance and texture of the skin's surface. Their benefits vary depending on the specific acid and formulation.

1. Help Improve Dull Skin

Dead skin cells can accumulate on the skin's surface, making it appear dull or uneven. AHAs help loosen this buildup and support surface exfoliation.

With appropriate use, AHA-containing products can help improve the appearance of dull skin and create a smoother-looking complexion.

2. Improve Uneven Skin Tone

AHAs are commonly used in skincare products formulated for uneven skin tone and certain forms of superficial pigmentation.

By encouraging the shedding of dead surface cells, they may help improve the appearance of dark spots and post-acne marks over time. They should not be considered a treatment for every type of pigmentation or a substitute for professional assessment when pigmentation is persistent.

3. Smooth Rough Skin Texture

Roughness can develop when dead skin cells accumulate on the outer layer of the skin. AHAs help exfoliate this surface buildup, which may make skin feel smoother.

Glycolic and lactic acid are commonly used in products designed to improve the appearance of uneven texture and surface roughness.

4. Improve the Appearance of Fine Lines

Some AHA-containing skincare products are formulated to improve the appearance of fine lines and surface wrinkles. Glycolic acid, in particular, has been studied for its effects on photoaged skin.

The results depend on the concentration, formulation and duration of use. Cosmetic exfoliants should not be expected to remove deeper wrinkles or replace professional skin treatments.

5. Help With Surface Exfoliation

AHAs loosen the bonds between dead skin cells, helping them shed from the skin's surface. This exfoliating action is the basis for many of their uses in skincare.

Different AHAs have different properties, so the most suitable option depends on your skin's needs and tolerance.

What Are the Benefits of BHAs?

BHAs, particularly salicylic acid, are commonly used for oily and acne-prone skin because of their ability to work within pores.

1. Help Unclog Pores

Oil, dead skin cells and other debris can accumulate inside hair follicles and contribute to clogged pores. Salicylic acid can penetrate oil-filled pores and help loosen this buildup.

This makes BHA-containing products useful for people who experience blackheads and congestion.

2. Help Manage Blackheads and Whiteheads

Blackheads and whiteheads are types of comedonal acne that develop when hair follicles become blocked.

Salicylic acid helps exfoliate within pores and loosen accumulated dead skin cells. It is therefore commonly included in products designed for blackheads, whiteheads and acne-prone skin.

3. Support Acne-Prone Skin

Salicylic acid is widely used in over-the-counter acne products. Its exfoliating action helps reduce the buildup that contributes to clogged pores.

It may be useful for some forms of mild acne, but persistent, painful or severe breakouts may need a dermatologist's assessment and a broader treatment plan.

4. Help Improve the Appearance of Congested Skin

Congested skin may feel uneven or appear to have visible blackheads and blocked pores. Salicylic acid helps loosen oil and dead skin cell buildup within pores, which may improve the appearance of congestion.

It does not permanently shrink pores. Rather, clearing accumulated material can make pores appear less noticeable.

5. Provide Exfoliation for Oily Skin

Because salicylic acid is oil-soluble, it is commonly used in skincare products for oily and combination skin. It can help address pore congestion without relying only on surface exfoliation.

However, using too much can cause dryness and irritation, including in people with naturally oily skin.

AHA vs BHA: Which One Should You Use for Your Skin Type?

The right exfoliating acid depends more on your main skin concern than on your skin type alone.

For dry or rough skin: An AHA such as lactic acid may be a suitable option if surface roughness and dullness are the main concerns. Choose a formulation that your skin tolerates and maintain moisturising care.

For oily or acne-prone skin: A BHA such as salicylic acid may be more suitable when blackheads, clogged pores and breakouts are the main concerns.

For combination skin: You may not need the same exfoliant across your entire face. Choose based on the specific concern and avoid over-exfoliating different areas.

For sensitive skin: Neither AHA nor BHA is automatically irritation-free. Consider avoiding exfoliating acids during active irritation and seek a dermatologist's advice if you have a skin condition or a compromised skin barrier.

Can You Use AHA and BHA Together?

Yes, AHA and BHA can be used together in certain skincare formulations or routines, but combining them is not necessary for everyone.

AHAs mainly target surface exfoliation, while BHAs such as salicylic acid work on surface buildup and within pores. A carefully formulated product containing both may address more than one concern.

However, applying separate high-strength AHA and BHA products together can increase the risk of dryness, redness, stinging and irritation.

If you want to use both:

• Introduce one acid at a time so you can assess your skin's response.
• Consider using them on alternate evenings rather than layering them immediately.
• Avoid combining multiple exfoliating products when your skin is still adjusting.
• Use a moisturiser to support skin comfort.
• Stop or reduce use if you develop persistent burning, peeling or irritation.

If you have acne, pigmentation or sensitive skin and are unsure how to combine active ingredients, consult a dermatologist.

How to Use AHAs and BHAs Safely

Using exfoliating acids correctly is important to reduce the risk of irritation and damage to the skin barrier.

1. Start With One Exfoliating Acid

Choose either an AHA or BHA based on your main skin concern. Avoid introducing several new active ingredients at the same time.

2. Begin Gradually

Start with a lower-strength product and follow its label instructions. If you are new to exfoliating acids, begin with occasional use rather than applying the product every day.

There is no single frequency suitable for everyone. It depends on the acid, concentration, formulation and your skin's tolerance.

3. Apply to Clean Skin

Use the product as directed. Some products are designed to be rinsed off, while others are leave-on serums or toners. Do not assume that every exfoliant should be used in the same way.

4. Follow With Moisturiser

Use a moisturiser after exfoliating to help maintain skin hydration and comfort. Avoid adding multiple strong active ingredients to the same routine if your skin is not accustomed to them.

5. Use Sunscreen During the Day

Sun protection is important when using exfoliating acids. The US Food and Drug Administration (FDA) specifically warns that topical AHA products may increase sensitivity to sunlight and the possibility of sunburn. It advises using sunscreen, protective clothing and limiting sun exposure while using these products and for a week after stopping them.

Follow the product's sun-protection instructions even when using a BHA product.

Possible Side Effects of AHAs and BHAs

Both AHAs and BHAs can cause side effects, especially when used too frequently, in high concentrations or in formulations that do not suit your skin.

Possible reactions include:

• Redness: Skin may appear red or irritated after application.
• Stinging or burning: A mild temporary sensation may occur, but persistent burning is a warning sign.
• Dryness: Exfoliation can leave skin feeling dry or tight.
• Peeling and flaking: Excessive use may cause visible peeling.
• Increased sensitivity: Skin may become more reactive to other skincare products or environmental factors.

AHAs can increase sensitivity to UV radiation, so daily sun protection is particularly important. BHAs can also cause irritation and should be used according to product directions.

If you experience persistent irritation, swelling, blistering or severe discomfort, stop using the product and seek medical advice. Avoid applying exfoliating acids to broken, sunburned or actively irritated skin unless a dermatologist has advised you otherwise.

Conclusion

When comparing AHA vs BHA, the main difference is where each type of exfoliating acid primarily works. AHAs, such as glycolic and lactic acid, focus on the skin's surface and are commonly used for dullness, rough texture and uneven tone. BHAs, especially salicylic acid, are oil-soluble and can work within pores, making them useful for blackheads, congestion and acne-prone skin.

Neither is automatically better. Choose an exfoliant based on your skin concern, introduce it gradually, moisturise regularly and use sunscreen during the day. If you have sensitive skin or persistent acne and pigmentation, a dermatologist can help you select the most appropriate option.