Chemical exfoliation is a core component of many modern skincare routines, yet it is frequently misunderstood. Alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs) are often discussed interchangeably, despite functioning very differently on the skin. Choosing between them requires an understanding of skin structure, oil solubility, and individual skin behaviour.
In Australia, exfoliation decisions are further complicated by high UV exposure, heat, and seasonal humidity, all of which influence barrier function and irritation risk. This article provides a clinical, evidence-based comparison of AHA and BHA exfoliants, focusing on how they work, who they are suitable for, and their limitations.
Neither AHA nor BHA is universally better.
What Are Chemical Exfoliants?
Chemical exfoliants work by weakening the bonds between dead skin cells, allowing them to shed more evenly. This process differs from physical exfoliation, which relies on friction.
Proper chemical exfoliation can improve texture, clarity, and ingredient penetration when used correctly.
Overuse can impair the skin barrier.
What Are AHAs?
Alpha hydroxy acids are water-soluble acids that work primarily on the surface of the skin. Common AHAs include glycolic acid, lactic acid, and mandelic acid.
AHAs are most effective for addressing surface concerns such as rough texture, dullness, and uneven tone.
They do not penetrate deeply into pores.
What Are BHAs?
Beta hydroxy acids are oil-soluble acids, with salicylic acid being the most common example. Their oil solubility allows them to penetrate into pores.
BHAs are particularly useful for oily and acne-prone skin, as they can dissolve sebum and debris within follicles.
They also have mild anti-inflammatory properties.
Depth of Action
AHAs act primarily on the outermost layers of the skin, improving surface smoothness and hydration behaviour.
BHAs work both on the surface and within pores, making them more suitable for congestion-related concerns.
Depth of action influences both effectiveness and irritation risk.
Skin Type Suitability
AHAs are often better tolerated by normal to dry skin types, particularly when hydration is a concern.
BHAs are generally preferred for oily, acne-prone, or congestion-prone skin.
Individual tolerance varies regardless of skin type.
Exfoliation and the Australian Climate
High UV exposure in Australia increases the risk of post-exfoliation sensitivity. Both AHAs and BHAs can increase photosensitivity, particularly AHAs.
Consistent sunscreen use is essential when using chemical exfoliants.
Exfoliation frequency should be adjusted seasonally.
Irritation and Barrier Risk
Excessive exfoliation can compromise the skin barrier, leading to redness, stinging, and increased breakouts.
AHAs may cause surface irritation, while BHAs may cause dryness or peeling with overuse.
Lower frequency often improves long-term tolerance.
Can AHAs and BHAs Be Used Together?
Some formulations combine AHAs and BHAs to target both surface texture and pore congestion. While effective for some users, combined use increases irritation risk.
Alternating use on different days is often safer than simultaneous application.
Combination routines require careful monitoring.
Exfoliation Frequency
Most skin types benefit from exfoliation one to three times per week. Daily exfoliation is rarely necessary and often counterproductive.
Frequency should be guided by skin response rather than product instructions alone.
More is not better.
Common Misconceptions
A common misconception is that tingling indicates effectiveness. In reality, discomfort often signals irritation.
Another misconception is that exfoliation is required for visible results; many skin concerns improve with barrier repair alone.
Exfoliation is optional, not mandatory.
Effective exfoliation supports skin function without compromising the barrier.
Clinical exfoliation principle
Final Perspective
AHAs and BHAs serve different purposes within skincare routines. AHAs primarily address surface texture and tone, while BHAs target pore congestion and oil-related concerns. For Australian skin exposed to high UV levels, cautious use, proper sun protection, and realistic expectations are essential. Choosing between AHA and BHA should be guided by skin behaviour rather than trends.