What are AHAs, What are BHAs – and Which is Right for Your Skincare Routine?

Chemical exfoliants can seem intimidating – at least at first. Yet they’re easier to use than most expect, and remarkably effective in revealing smoother, brighter skin.

The most common types are AHAs (alpha hydroxy acids) and BHAs (beta hydroxy acids), two exfoliating ingredients that help lift away dull surface cells and refine texture for a more radiant complexion.

So, what are BHAs and AHAs?

Read on to learn how to use these exfoliating acids to even skin tone, enhance glow, and prepare your skin for stronger, longer-lasting results.

What are AHAs?

AHAs – alpha hydroxy acids – are water-soluble exfoliants that work on the skin’s surface to remove dull, dead cells and uncover a smoother, more luminous layer underneath.

Derived from natural ingredients, such as milk and sugar cane, AHAs help accelerate the skin’s natural shedding process to improve texture, fine lines, and visible dullness.

Common AHAs include:

• Glycolic acid

• Lactic acid

• Citric acid

What are BHAs?

BHAs – beta hydroxy acids – are oil-soluble exfoliants that work both on the surface of the skin and within the pores. Their ability to penetrate deeply helps unclog congestion, making them ideal for oily or blemish-prone skin types.

Common BHAs include:

• Salicylic acid

• Tropic acid

• Lipo-hydroxy acid (LHA)

AHAs vs BHAs: What’s the difference?

While both dissolve the bonds between dead skin cells and promote cell turnover, the key to understanding the AHAs vs BHAs distinction lies in how they interact with the skin.

• AHAs are water-soluble, meaning they work on the skin’s surface to refine texture, boost radiance, and reduce the look of fine lines, sun damage, and dryness.

• BHAs are oil-soluble, allowing them to penetrate deeper into pores to clear build-up and reduce blackheads, breakouts, and excess oil.

In short, AHAs target surface concerns and hydration, while BHAs excel at deep pore cleansing and clarity.

AHAs vs BHAs: Which is right for your skincare routine?

Both acids can deliver impressive results when used correctly – the key is finding the right fit for your skin type and introducing them gradually.

• For dull-looking or dry skin, AHAs are beneficial for their hydrating and exfoliating abilities. They help support the skin moisture barrier and reveal a smoother, more radiant finish.

• For oilier or blemish-prone skin, BHAs are a better match. Known for their soothing properties, BHAs help clear pores without over-drying, balancing the skin while maintaining hydration.

Many routines can benefit from using both, as AHAs and BHAs target different concerns. The key is balance – start slowly and monitor how your skin responds. If you notice discomfort that persists, it’s best to consult a dermatologist.

Not sure where to start when it comes to choosing AHAs and BHAs for your regimen? Find your skin type and create a routine that fits with our online Healthy Skin Routine Finder.

How to use AHAs and BHAs safely

Understanding what BHAs are – and what are AHAs in skincare, too – also means knowing how to use them correctly. These are powerful exfoliants, so correct application is essential. Over-exfoliation can weaken the skin moisture barrier and lead to irritation.

Before applying:

• Always patch-test under your jawline to identify potential sensitivities

• Introduce gradually – once or twice a week – before increasing frequency.

To apply:

1. Start with clean, well-hydrated skin – avoid if sunburnt or irritated.

2. Apply a pea-sized amount of exfoliant evenly to the face.

3. Follow with hydrating serums or moisturisers to lock in moisture.

4. Always finish with SPF, as exfoliants can increase sun sensitivity.

Usage may vary depending on the product, so always follow the specific directions provided with each formula.

Kiehl’s products with AHAs and BHAs

At Kiehl’s, we look at these powerful exfoliants not in terms of AHA vs BHAs, but AHAs and BHAs – how they can work together, rather than against each other, to support the long-term balance of your skin.

Ultra Facial Cleanser

For example, our Ultra Facial Cleanser is formulated with the AHA, citric acid, which works on the skin’s surface to gently remove excess oil and buildup. Enriched with hydrating ingredients like avocado oil and squalane, it helps maintain moisture for skin that feels clean, balanced, and comfortable.

Gentle enough to wash your face with every day, this formula is suitable for all skin types.

Clearly Corrective™ Daily Re-Texturizing Triple Acid Peel

When your skin calls for deeper renewal, our Clearly Corrective™ Daily Re-Texturizing Triple Acid Peel is a gentle, yet effective, peel that provides triple-acid power in one step.

Featuring AHAs and BHAs, it visibly refines pores, smooths texture, and boosts overall luminosity. Working below the surface to even tone and support a damaged skin moisture barrier, it’s suitable for all skin types and can be used up to twice daily.

Simply apply a thin, even layer and allow it to absorb completely before following with our Ultra Facial Cream with Squalane – a lightweight, everyday moisturiser for balanced hydration.

Avocado Nourishing Hydration Mask

To replenish moisture, our Avocado Nourishing Hydration Mask is a creamy, nutrient-rich mask infused with citric acid, an AHA. Blended with shea butter, avocado oil, and avocado extract, it can help nourish and hydrate the skin within 15 minutes.

Suitable for all skin types, it’s best used up to three times per week to maintain balance and lasting hydration.

You’ve learned what are AHAs and BHAs in skincare – next, discover the myriad benefits of calendula for your skin.

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Kiehl’s Ultra Facial Cleanser tube - gentle foaming facial cleanser for all skin types

Kiehl’s facial foaming cleanser formula swatch featuring a smooth, lightweight texture.

Hand demonstrating application of a foaming cleanser formula on face.

Ultra Facial Cleanser

A foaming facial cleanser suitable for all skin types, including dry and sensitive. Gently removes excess oil, dirt and debris without drying or stripping the skin.

One size only

150 ml

Old price New price A$54.00