- AHA’s are chemicals exfoliants that slough off dead cells to gradually reveal brighter, smoother skin
- Common AHAs include glycolic, lactic and mandelic acid
- These exfoliants are safe for all skin types, with a few caveats
Chemical exfoliants fall into several categories determined by their molecular properties. One category is alpha-hydroxy acids (AHAs), the most popular type of chemical exfoliant. AHA exfoliants include multiple types of acids with varying strengths.
AHAs treat various signs of aging and sun damage, including mild hyperpigmentation and fine lines, to help your skin appear smoother and younger. Your skin type and the skin concerns you need to address will determine which AHA exfoliant is right for you.
What Are AHAs?
AHAs are derived from fruit sugars. They’re water-soluble, meaning they are effective at removing surface-level imperfections but don’t penetrate too deeply into pores.
AHAs chemically exfoliate by loosening the bonds that hold dead cells to the skin’s surface. They are most effective at treating mild hyperpigmentation, enlarged pores, fine lines, wrinkles and uneven skin tone. They also help other products better absorb into the skin.
AHAs are an active ingredient in a large range of exfoliating skin care products including:
Glycolic acid, derived from sugar cane, is one of the most popular AHAs due to the large body of research supporting its effectiveness. This acid has a small molecular size, meaning that even though it’s not oil-soluble, its molecules nevertheless deeply penetrate pores. The acid breaks up the bonds holding skin cells together, allowing dead cells to be easily rinsed away.
It is used as both a chemical peel and as an ingredient in everyday skin care products. In leave-on products such as creams or serums, it’s typically found in concentrations of 5–10%.
A peel may contain up to 50% glycolic acid; these at-home kits should be used with caution as improper usage could irritate or burn your skin.
Lactic acid, another popular AHA, is derived from the lactose in milk. It is considered milder than some other AHAs but still has significant exfoliating properties. Similarly to glycolic acid, lactic acid loosens dead cells from the skin’s surface, revealing brighter, smoother skin beneath.
Lactic acid is found in a large range of skin care products, usually at concentrations between 5–30%.
Extracted from apples, malic acid is not a very effective exfoliant on its own and so is rarely a primary active ingredient. However, it can increase the effectiveness of other AHAs when used in combination. For this reason, most products that contain malic acid also contain another AHA.
Mandelic acid has a larger molecular size, making it a slow-acting exfoliant that is gentle enough for sensitive skin types.
Whereas many AHAs can cause discoloration in dark skin at higher concentrations, mandelic acid has been demonstrated to effectively and safely lighten hyperpigmentation in dark skin when used in combination with salicylic acid.
Tartaric acid, an AHA derived from grapes, is usually used alongside glycolic or lactic acid as a buffering agent to help stabilize the product’s pH. It is an antioxidant that protects the skin from damaging free radicals and UV rays, and is less likely to cause irritation or other side effects than other acids.
How Do AHAs Exfoliate?
As a topical application, AHAs break up the bonds between dead cells in the stratum corneum, the protective outermost layer of skin. Once those bonds are weakened, the cells easily slough off.
Eliminating these dead skin cells promotes the renewal of healthier cells beneath. With consistent use, AHAs will slowly but noticeably soften or remove imperfections from the skin.
AHAs are proven to lighten hyperpigmentation, reduce the appearance of fine lines and give skin a softer, smoother overall appearance. With regular use, they can also reduce build-up in pores, to prevent the formation of pimples and blackheads.
Additional benefits include an increase in moisture, collagen production and skin thickness.
Are AHA Exfoliants Right for You?
AHAs are considered safe for all skin types. They are ideal for anyone dealing with hyperpigmentation, sun damage or signs of aging or who simply wants to keep their skin smooth and fresh.
However, your skin type determines how often and in what concentrations you should use them, as some skin types are more tolerant than others.
Acne-prone skin has an excess of sebum, the oil naturally occurring in skin. In general, it can easily tolerate glycolic acid. In addition to deeply exfoliating, glycolic acid has antimicrobial properties and has been demonstrated to improve mild acne.
Mandelic acid has been proven to reduce multiple types of acne lesions, including papules, nodules and comedones such as whiteheads or blackheads.
Due to its anti-inflammatory properties, tartaric acid is also commonly recommended for acne-prone skin.
AHAs work well to address common issues of dry skin including fine lines, sun damage and roughness. However, it’s important not to overexfoliate and strip your skin of further moisture.
Lactic acid has strong moisturizing properties and is therefore ideal for this skin type.
As sensitive skin can easily react to most any skin care products, those who fall within this category should exercise caution when applying AHAs.
Opt for a product that contains a low percentage of the active ingredient (less than 5%) and use only 1–2 times a week. Choose products that contain lactic or mandelic acid, the mildest of the AHAs. If you are using a rinse-off product, aim for the lower end of the recommended leave-on time.
Your skin may gradually build up a tolerance to AHAs, but if you experience any redness or irritation, decrease your frequency of use.
How to Use AHA Exfoliants
Follow the product instructions as directed for safety and for the best results. If there is a recommended leave-on time, you may wish to err on the safe side to test your skin’s reaction.
To test for any negative reactions, perform a spot test first. If you start to feel any burning or tingling, wash the product off immediately.
As a rule, AHAs are best used at night to allow your skin time to recover and rejuvenate while you sleep.
Regular AHA use increases your skin’s sensitivity to the sun. Apply a moisturizer containing a sunscreen of at least 30 SPF every morning while using AHA products.
How often should you use AHA exfoliants?
Regardless of what concern you’re targeting, the frequency at which you apply AHAs depends on your skin type, how well you tolerate the acids and the type of products you use.
Many products such as exfoliating cleansers, wipes and toners indicate that they are safe for daily use. However, individuals with dry or sensitive skin may find their skin can only tolerate these products 1–2 days a week, even after several months.
The safest way to use these products is to monitor your skin for any irritation.
Some products, such as peels, contain high concentrations of active ingredients and should only be used a few times a month.
AHAs vs. BHAs
Whereas AHAs are water-soluble, beta-hydroxy acids (BHAs) are oil-soluble. This property means they are better able to penetrate more deeply into clogged pores and dissolve sebum. The most common BHA is salicylic acid.
Because BHAs reduce acne and dry out excess sebum, they are well-suited to oily, acne-prone skin. People with this skin type may find that BHAs used in tandem with AHAs keep their skin clearer and smoother than AHAs alone, whereas people with dry skin may not need BHAs at all.
Retinoids offer a number of skin care benefits and address many of the same issues as AHAs. They can reduce signs of aging, including fine lines, wrinkles and uneven skin tone. Retinoids can also treat acne symptoms.
Lastly, for a simple approach, you may opt for one of the many gentle facial scrubs designed for your skin type. You can also create your own natural scrub at home with a DIY recipe you can customize for your skin.
AHAs are exfoliating acids usually derived from fruit sugars. The most common AHAs are glycolic, lactic, mandelic, malic and tartaric acid. They’re found in an extensive range of skin care products including face washes, moisturizers, serums and peels.
With consistent use, AHAs can effectively treat a range of skin conditions including acne, hyperpigmentation, sun damage and many signs of aging.
Dry skin types benefit most from glycolic or lactic acid. If you have sensitive skin, lactic or mandelic acid are the least likely to cause a skin reaction. Individuals with acne-prone or oily skin can safely use mandelic, glycolic or tartaric acid.
As an alternative to AHAs, BHAs, another class of chemical exfoliant, may be particularly effective for oily skin. Retinoids are another solution for many of the skin issues that AHAs seek to correct.
If your skin cannot tolerate any acids, consider a mild facial scrub to keep your skin exfoliated and feeling fresh.
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