Alpha Hydroxy Acid (AHA) Exfoliant Benefits for the Skin
If you’re on a quest for younger-looking, smoother, and more even-toned skin, you may have heard of the exfoliant called alpha hydroxy acid (AHA). But what exactly is an AHA exfoliant? And with several types of AHAs available, how do you know which one is best for treating dull, lacklustre skin?
Think of this as your cheat sheet on all things AHA-related. In this guide, you’ll learn how AHAs work and what sets each type apart.
What are Alpha Hydroxy Acids (AHAs)?
AHAs work by loosening the bonds between dead skin cells so they shed more easily through a controlled, gentle exfoliation process. This form of thorough exfoliation reveals fresher, more refined skin that looks smoother and more hydrated — and, over time, becomes visibly firmer. Anyone concerned with maintaining younger-looking skin for longer should consider adding an AHA exfoliant to their routine.
1. Glycolic Acid
Among all of the alpha hydroxy acids, glycolic acid is considered the gold standard. It’s the most researched and, along with lactic acid, has one of the strongest track records for delivering impressive results across all ages and all skin types.
What makes glycolic acid so effective is its small molecular size which allows it to penetrate the upper layers of built-up skin and reveal the fresher-looking skin beneath. It also has a natural ability to hydrate by drawing water into the skin, helping it stay moisturised and giving it a healthy, hydrated glow as it exfoliates.
If that weren’t enough, glycolic acid used alone or with other AHA exfoliants at concentrations of 5% and above can help improve the look of firmness and resilience while softening the visible signs of sun damage.
Although glycolic acid can be derived from sugarcane, the synthetic form is more commonly used in skincare because it allows for better stability and consistent percentages. At Paula’s Choice Skincare, we offer several glycolic acid exfoliants to suit different skin types and concerns.
2. Lactic Acid
Lactic acid offers many of the same benefits as glycolic acid, but it works a bit more gradually because its molecule is slightly larger. This larger molecular size limits how deeply it can penetrate the skin’s outermost layer. At concentrations of 2% and above, topical lactic acid helps hydrate the skin. When used alone or in combination with other AHAs, it begins working as an exfoliant at a 5% concentration, with 5% to 10% being the ideal range for effective exfoliation. Lactic acid is also known for helping improve the look of dark spots and promoting a more even skin tone.
Although lactic acid can be derived from milk, the synthetic form is most often used in skincare products because it provides better stability and more consistent results.
3. Malic Acid
Malic acid can be derived from apples or produced synthetically, with the synthetic version being the preferred choice in skincare for the same stability and consistency reasons as glycolic and lactic acids.
Its molecules are larger than those of glycolic and lactic acid, but malic acid can still provide gentle exfoliation while offering antioxidant benefits. At concentrations of 1% to 2%, it works well as a supporting AHA alongside glycolic and lactic acid, contributing to a nice multi-level exfoliation effect. You’ll find these AHA blends in select leave-on exfoliants as well as rinse-off peels.
4. Tartaric Acid
Tartaric acid molecules are larger compared to malic acid and are nearly twice as large as glycolic acid molecules. It occurs naturally in grapes but is also produced synthetically, which is the form most commonly used in skincare products for better stability and consistency.
Although tartaric acid can exfoliate when used in roughly the same concentrations as glycolic or lactic acids, it functions best in helping to maintain an ideal pH range so that other skincare products containing AHAs can work their magic. In certain formulas, it helps provide more targeted exfoliation, as each size of AHA has its layer-by-layer benefits.
5. Citric Acid
Citric acid can be derived from citrus fruits or produced synthetically. Although higher concentrations (around 10% and above) can provide exfoliation, citric acid is more likely to be irritating due to its naturally low, skin-sensitising pH of about 2.2.
In lower amounts, citric acid is commonly used in skincare as both an antioxidant and a pH adjuster, helping formulas stay within an effective yet gentle pH range.
Some AHA products include citrus extracts that are sometimes marketed as “natural AHAs.” While this may sound appealing, current research has not shown these extracts to be effective exfoliants. Their fragrant components can also be sensitising for skin, which makes them less suitable for gentle, leave-on exfoliation.
6. Mandelic Acid
Mandelic acid is less commonly used than other AHAs due to limited research, but its large molecular size gives it slower penetration, making it a gentler option for sensitive skin and combination acne-prone skin. It can help improve the look of acne, post-breakout hyperpigmentation, and uneven skin tone with a lower risk of irritation.
High-strength mandelic acid peels (around 40%) have been shown to increase oil production, which may not suit oily or stubborn acne-prone skin but can benefit drier skin types.
There are no standardised concentration guidelines for mandelic acid in leave-on products, as most studies use professional peel strengths (20–40%), far higher than those found in daily skincare.
Discover Paula’s Choice products for oil control and dull skin.
References for this Information
Skincare benefits of alpha hydroxy acid (AHA), and how to use it; Medical News Today
Benefits of glycolic acid for the skin; Medical News Today
National Library of Medicine, Dual Effects of Alpha-Hydroxy Acids on the Skin
MDPI, Topical AHA in Dermatology: Formulations, Mechanisms of Action, Efficacy, and Future Perspectives
PubMed Central, Evaluating the Efficacy and Safety of Alpha-Hydroxy Acids in Dermatological Practice: A Comprehensive Clinical and Legal Review
Molecules, April 2018, Volume 23, Issue 4, page 863
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