If you’re looking to achieve smooth, supple, radiant skin, exfoliating should form part of your skincare routine. Though your skin naturally sheds dead skin cells every thirty days or so, this process slows down over time, resulting in dry, dull, congested skin, as well as the appearance of enlarged pores, poor skin texture, and uneven skin tone. Exfoliation gives your skin a helping hand, removing the buildup of dead skin cells and revealing smoother, softer, more hydrated skin. For best results, steer clear of granular formulas involving harsh ingredients like walnut shells and microbeads which can damage the skin’s barrier and turn to chemical exfoliation instead; alpha hydroxy acids—or AHAs—are a group of chemical exfoliant which can be utilised by almost any skin type.
Read on for everything you need to know about using AHA in your skincare routine.
What is AHA?
AHA stands for alpha hydroxy acid, which are acids derived from sugar cane or other fruit sources. Alpha hydroxy acids include glycolic acid (from sugarcane), lactic acid (from sour milk), mandelic acid (from bitter almonds), malic acid (from apples), tartaric acid (from graphes), and citric acid (from lemons and other citrus fruits), with the first two being the most commonly used in skincare products. While these alpha hydroxy acids have natural sources, many skincare products use synthetically produced variants, which are more shelf stable.
AHAs, or alpha hydroxy acids, exfoliate the uppermost layers of the skin by loosening the bonds between skin cells which allow them to detach (i.e. shed) more easily. Shedding these older dead skin cells reveals the newer skin cells underneath, resulting in fresher, more radiant skin.
While all alpha hydroxy acids chemically exfoliate the top layers of the skin, they differ in molecular size which affects their penetration and potency. AHAs with a smaller molecular size will penetrate the skin more deeply, resulting in a more thorough exfoliation. However, this higher efficacy is accompanied by an increased likelihood of irritation, making it important to consider the type of alpha hydroxy acid you use, as well as its concentration within a formula.
What are the benefits of alpha hydroxy acids (AHAs) for skin?
Alpha hydroxy acids are water-soluble acids that work on the surface of the skin, dissolving the bonds that keep dead skin cells attached to the outer layer of the skin and allowing these to be sloughed off. This results in a visible improvement in skin texture and dullness. With continued use, AHAs brighten the skin, fade dark spots and discolouration, promote skin cell turnover, and reduce the appearance of wrinkles and fine lines.
Certain alpha hydroxy acids can also be beneficial for those with dry skin. Glycolic, lactic, and malic acid are humectants, which means they attract and bind water to the skin, leaving skin feeling supple and hydrated.
By sloughing off dead skin cells, AHAs enhance the absorption—and thereby efficacy—of other skincare products such as serum and moisturiser.
While BHA is typically recommended for those with acne-prone skin, AHAs can also help decrease congestion by eliminating dead skin cells which may clog the skin and result in breakouts.
Who should use AHAs?
According to Desiree Stordahl, Senior Research & Education Manager at Paula’s Choice, alpha hydroxy acids are preferred for dry to normal, as well as mature and sun-damaged skin, thanks to their ability to enhance the natural moisturising factors within the skin.
Those with oily and acne-prone skin are often recommended to use beta hydroxy acid (BHA) due to its ability to penetrate more deeply into the pores and clear out excess sebum. That said, there are products which combine AHAs and BHA, which can be beneficial for oily skin types.
Those with sensitive skin can use AHAs, however it’s recommended to start with a low concentration and pick an AHA with a larger molecular size to prevent irritation.
Can you use AHA with retinol and other skincare active ingredients?
“You can absolutely use an AHA alongside retinol; they don’t deactivate one another,” says Stordahl, adding that “if anything, AHAs actually help retinol work better by removing dead skin, so you get optimal penetration. The same goes for other acids like azelaic acid or ascorbic acid (i.e. vitamin C).”
As for BHAs like salicylic acid, Stordahl says that “while most people do well with sticking to just one AHA or BHA exfoliant, some people find alternating between both works that much better to reveal [the] skin’s optimal smoothness and healthy tone. If you want to use both, all you need to do is alternate application, [using] one in the morning and the other at night, or rotate days.” Alternatively, she suggests using “a product that properly combines AHA and BHA together in one formula.”
What are the types of alpha hydroxy acids (AHAs)?
As mentioned earlier, there are several types of AHAs, each derived from various sources and with different molecule sizes and skincare benefits. Here, we run through the types of alpha hydroxy acids worth knowing about, from glycolic and lactic to mandelic and malic.
- Glycolic acid: likely the most popular AHA, glycolic acid is derived from sugarcane or created synthetically and has a very small molecule size which allows it to penetrate the uppermost layers of the skin more deeply. Of all the alpha hydroxy acids on the market, glycolic acid yields the most significant results, however it also has a propensity to cause irritation. Those with sensitive skin should use a lower concentration of glycolic acid or opt for an AHA with a larger molecule size.
- Lactic acid: naturally found in sour milk or produced synthetically, lactic acid has a slightly larger molecular size than glycolic acid. It’s a natural humectant and can hydrate the skin in low doses, with percentages of between 5% and 10% used in leave-on topical exfoliants.
- Malic acid: derived from apples or produced synthetically, malic acid has a larger molecule size than both glycolic and lactic acid, however is still able to provide a good exfoliation with consistent use. It’s often used as a supporting act within leave-on and rinse-off AHA exfoliants, in smaller percentages alongside other alpha hydroxy acids.
- Tartaric acid: found naturally in grapes or produced synthetically, tartaric acid is larger than malic acid and almost twice the size of glycolic acid. While it does exfoliate on its own, it’s typically used at concentrations ranging from 1% to 10% in formulas with other AHAs; both for its exfoliating properties as well as its ability to maintain an optimal pH range within a product formula.
- Citric acid: found in various citrus fruits such as lemon and orange, citric acid has a low pH level and can be irritating to the skin on its own. For that reason, it’s often used in a low dose within other skincare products (including cleansers, exfoliants, and masks) to maintain optimal pH levels.
- Mandelic acid: found in bitter almonds, mandelic acid is the largest AHA. Its larger molecule size means it takes longer to penetrate the skin, making it a viable option for gentle exfoliation for those with sensitive skin. It’s typically used as a leave-on product, with consistent use yielding results.
What is the difference between AHAs and BHA?
As mentioned earlier, AHAs are water-soluble and work on the surface layer of the skin (the epidermis). This makes them useful for treating uneven skin texture, hyperpigmentation, fine lines, and dull skin.
In contrast, BHA—the most popular beta hydroxy acid for skincare being salicylic acid—is an oil-soluble acid that is able to penetrate beneath the skin’s surface and clear out excess sebum from the pores. This makes it effective in regulating sebum production for those with oily and acne-prone skin.
How to incorporate an AHA exfoliant into your skincare routine
Leave-on alpha hydroxy acids should be used after cleansing and toning, before applying any other serums. Additionally, AHAs can cause the skin to be more sensitive to the sun, making it essential to wear a broad spectrum SPF during the day.
Rinse-off AHA exfoliants (such as face masks) can be used once to twice a week at nighttime.
Can you use an AHA exfoliant every day?
Leave-on AHA exfoliants in low to moderate doses (2% to 10%) can be used daily. Products with a higher dose (10% to 25%) such as rinse-off masks should be limited to use once or twice a week to avoid disrupting the skin barrier.
The best leave-on and rinse-off AHA exfoliants to try in 2025
1. Alpha-H Liquid Gold
Something of a cult-favourite both domestically and overseas, homegrown brand Alpha-H’s Liquid Gold combines 5% glycolic acid with brightening liquorice root extract and silk proteins which help prevent transepidermal water loss. A low-pH delivery system ensures the glycolic acid is at its most active, while the moderate concentration allows it to be used daily or on alternating days.
Price: $76.95AUD
Acid type: 5% glycolic acid
2. Sunday Riley Good Genes Lactic Acid Treatment
A powerful overnight leave-on treatment, the Sunday Riley Good Genes Lactic Acid Treatment pairs lactic acid with brightening liquorice extract and calming prickly pear extract to deeply exfoliate the skin overnight. Expect to awaken with smoother, more radiant skin, with consistent use working to fade dark spots and hyperpigmentation.
Price: $147AUD
Acid type: 7% lactic acid
3. Paula’s Choice 6% Mandelic Acid + 2% Lactic Acid Liquid Exfoliant
Designed with sensitive skin in mind, the Paula’s Choice 6% Mandelic Acid + 2% Lactic Acid Liquid Exfoliant combines mandelic acid—an AHA with a larger molecular weight—with a low dose of lactic acid to provide a multi-layered exfoliation without compromising the skin barrier. It’s also enriched with a fermented antioxidant blend of cherry blossom, chocolate vine, and bayberry to support the skin’s microbiome.
Price: $54AUD
Acid type: 6% mandelic, 2% lactic
4. Biossance Squalane + 10% Lactic Acid Resurfacing Night Serum
A gentle yet efficacious overnight treatment, the Biossance Squalane + 10% Lactic Acid Resurfacing Night Serum attenuates any potential irritation associated with AHA exfoliant use with the brand’s signature squalane. The addition of squalane locks in moisture and strengthens the skin barrier, while lactic acid sloughs off dead skin cells and draws moisture into the skin.
Price: $114AUD
Acid type: 10% lactic acid
5. Paula’s Choice 25% AHA + 2% BHA Exfoliant Peel
The closest thing you can get to a clinical treatment in a tube, the Paula’s Choice 25% AHA + 2% BHA Exfoliant Peel is a heavy hitting treatment that combines five types of AHAs with salicylic acid to provide a multi-layered exfoliation that refines the skin and clears pores of excess sebum. A rinse-off treatment, the Paula’s Choice 25% AHA + 2% BHA Exfoliant Peel is recommended for use once a week, with consistent use working to effectively fade post-inflammatory hyperpigmentation, age spots, and dark marks, while reducing the appearance of fine lines.
Price: $66AUD
Acid type: 8.4% glycolic acid, 7.1% lactic acid, 5% mandelic acid, 2.5% malic acid, 2% tartaric acid, 2% salicylic
6. Ole Henriksen Dewtopia 20% Acid Night Treatment
Another product that masters the art of multi-level exfoliation, the Ole Henriksen Dewtopia 20% Acid Night Treatment combines 10% glycolic and lactic acids with 10% polyhydroxy acids, which have a larger molecular structure and are more gentle on the skin. The glycolic and lactic acids penetrate deeper into the skin, while polyhydroxy acid works on the skin’s surface, providing a more thorough exfoliation.
Price: $90AUD
Acid type: 10% glycolic and lactic acid (exact breakdown unspecified), 10% polyhydroxy acids
7. The Ordinary Glycolic Acid 7% Exfoliating Toner
The Ordinary Glycolic Acid 7% Exfoliating Toner has been around for—way longer than—a hot minute, but it’s a classic for a reason. A straightforward exfoliating toner, its glycolic acid content penetrates the skin quickly and delivers quick results. For that reason, it’s best to ease into this one by using it a couple of times a week and working your way up to prevent irritation. It has a non-sticky, water-thin consistency and sinks into the skin immediately, with its use extending beyond the face and onto the body — including on dark underarms and knees.
Price: $13.70AUD
Acid type: 7% glycolic acid
8. Allies Of Skin Mandelic Pigmentation Corrector Night Serum
Equally focused on exfoliation as it is recovery from said exfoliation, the Allies Of Skin Mandelic Pigmentation Corrector Night Serum combines mandelic, salicylic, and lactic acids with a nourishing blend of niacinamide, hyaluronic acid, and fatty acids from rosehip and tamanu oils. There’s also bakuchiol (a phyto-retinol alternative) and peptides, which encourage skin firmness and reduce redness. With multiple molecular sizes of AHAs as well as BHA, it exfoliates both the upper and deeper layers of the skin, reducing discoloration and congestion and brightening skin over time.
Price: $181AUD
Acid type: 11% mandelic, lactic, and salicylic acids (exact breakdown unspecified)
9. Fresh Lotus AHA Gentle Resurfacing Serum
Gentle enough to be used daily, the Fresh Lotus AHA Gentle Resurfacing Serum combines a low dose of glycolic and citric acids with prickly pear flower extract to create a serum that reveals smoother, more radiant skin without causing irritation.
Price: $98AUD
Acid type: glycolic acid, citric acid (percentages unspecified)
10. Go-To Exfoliating Swipeys
Ideal for beginners and lazy girls (or guys) alike, Go-To Exfoliating Swipeys make exfoliation easy. Each single-use pad comes pre-soaked with a moderate dose of lactic acid and soothing aloe vera. The double-sided pads have a slightly abrasive surface on one side, allowing for a light physical exfoliation.
Price: $46AUD
Acid type: 5% lactic acid
11. Skinstitut Expert Glycolic Refining Solution
This elegantly formulated toner sees a moderate dose of glycolic acid paired with tonifying witch hazel and soothing aloe vera and green tea extract which work cohesively to fade pigmentation and brighten the skin without causing irritation.
Price: $59AUD
Acid type: 5% glycolic acid
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Words by Arabella Johnson
Feature image courtesy of Helmut Newton for Vogue Italia
