Figuring out how to use chemical exfoliants based on your skin type and concerns to achieve a healthy complexion can save you money, time, and spare you from skin irritation.
For many people, exfoliation is a key step in their skincare routine, as it helps to easily get rid of dead skin cells to reveal a healthier looking, smoother, brighter, and more even skin tone.
Before opting to incorporate an exfoliation into your skincare regime, it is worth taking into account your skin type, your skin tone and needs, because different exfoliation methods serve different skin types and concerns.
People with darker skin tones ought to be mindful of using very strong exfoliation to avoid triggering skin inflammation, which might in turn lead to post-inflammatory pigmentation disorders.
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Two types of exfoliation exist: physical and chemical. Chemical exfoliation, which is based on a range of acids such as AHAs, BHAs, and PHAs amongst other active ingredients, is currently experiencing a surge in popularity. They can be found in a wide range of beauty products including toners, cleansers, moisturisers, chemical peels, and facial serums.
This is due to consumers’ perceived affordability and efficacy of acid based skincare products in the treatment of stubborn skincare issues such as acne, scars, fine lines, wrinkles, skin discoloration, dark spots, hyperpigmentation, and uneven skin tone.
With the rise in popularity of exfoliating acids, let us look at the difference between AHAs, BHAs and PHAs, how they are used to support skincare needs, which ones are the most suitable for your skin type and concerns, and how to use them to achieve a healthy glow.
Alpha Hydroxy Acids (AHAs)
Alpha hydroxy acids (AHAs) are plant and animal-derived or synthetically produced acids that are used as superficial peeling agents in many cosmetic formulations to exfoliate the skin. The majority of AHAs used in cosmetic formulations are synthetically manufactured, because they are much easier to blend and stabilise with other beauty ingredients.
As water-soluble ingredients, AHAs primarily work on the outer layer (the surface) of the skin by dissolving the bonds between oil and dead cells, speeding up the skin cells renewal process. The level of exfoliation you will experience depends on the concentration of AHA, its pH level, and the additional ingredients found in the beauty product.
Through their exfoliating process, AHAs help improve your overall skin texture, brighten your complexion, even out your skin tone, and fight off mild skin discoloration from scars and age spots. Depending on product formulation, AHAs can also help promote collagen, prevent acne breakouts, improve the appearance of fine lines and wrinkles, and prepare the skin to better absorb other skincare ingredients.
The most common and well researched AHAs in cosmetic products are glycolic acid and lactic acid. Among other AHAs are mandelic acid, citric acid, hydroxycaprylic acid, and hydroxycaproic acid, tartaric acid, and malic acid.
In relation to glycolic acid and lactic acid, on precautionary principles, the SCCNFP in the European Union suggested that glycolic acid may be used safely at a level of up to 4% and a pH ≥ 3.8, and lactic acid may be used up to a maximum level of 2.5 % and a pH ≥ 5.0.
On the other hand, the FDA concluded that products containing glycolic and lactic acid are safe for use if the AHA concentration is 10% or less; the final product has a pH of ≥ 3.5; the final product protects the skin from increased sun sensitivity or promotes sun protection.
Because of their lower skin penetration and depending on the AHA concentration in a formula, AHAs work best for sun-damaged skin, people seeking to improve their skin tone and the appearance of fine lines and wrinkles, and correct mild hyperpigmentation.
People with sensitive skin or dry skin are better off going for over-the-counter cosmetic products with the right concentration of lactic acid and mandelic acid as the main AHAs, because they tend to be gentler on the skin. Their bigger molecular weights compared with glycolic acid, which has the smallest molecular weight of all the AHAs, slightly reduce their ability to penetrate the skin’s outermost layer, making them less irritating on skin, particularly for darker skins.
Lactic acid is found in a wide range of products, such as:
- REN Clean Skincare Ready Steady Glow Daily AHA Tonic 250ml
- NIOD Fractionated Eye Contour Concentrate Serum 15ml
- Eucerin® Dermo PURIFYER Scrub (100ml)
Although glycolic acid could be safely and effectively used on melanin-rich skin, many skincare experts either advise against it in light of its high potency, or they recommend seeking professional dermatological support in doing so to ensure optimum results.
Like lactic acid, glycolic acid is found in a variety of products, such as:
- PIXI Glow Tonic 250ml
- Beauty Pie Dr Glycolic™ Multi-Acid (6.5%) Micropeeling Pads
- Caudalie Vinoperfect Dark Spot Correcting Glycolic Night Cream 50ml
Studies have demonstrated that AHAs could trigger skin irritation and increase the sensitivity of skin to ultraviolet radiation.
Consequently, to allow your skin to get used to alpha hydroxy acids, you should only initially apply the skincare product every other day, gradually working up to daily application, depending on your skin tolerance and as recommended by the product manufacturer. Always, use daily sun protection that should be reapplied every two hours all year round to protect your skin from damaging sun radiation.
Beta Hydroxy Acids (BHAs)
Beta hydroxy acids (BHAs) are exfoliants made from sugary fruits that work to remove dead skin cells and excess sebum from the skin. Most of the BHAs found in cosmetic products are synthetically formulated to optimise product stability, safety and efficacy.
BHAs have similar exfoliating benefits to AHAs. However, as oil-soluble cosmetic ingredients, BHAs work both on the skin’s surface and deep inside the pores to improve your overall skin texture, fine lines, and unclog pores to remove acne-causing sebum, revealing a smoother and more youthful looking skin.
The deeper working BHA acids are generally included in formulas for acne treatment and in beauty products designed to help calm down skin irritation and inflammation. They work best for oily, acne-prone skin and combination skin that require targeted topical treatments.
Read More: 6 Best Tips To Treat Acne in Skin of Colour
*Salicylic acid (and related substances salicylate, sodium salicylate, lipophilic salicylic acid derivative named β-lipohydroxy acid, and willow extract) is the most commonly used and well researched BHA ingredient for cosmetics formulations.
According to the FDA, *from a chemist’s perspective however, salicylic acid is not a true BHA, even though it is a derivative of benzoic acid, which is part of the hydroxy acids in a broader sense, but displays different effects than other hydroxy acids.
Salicylic acid is a Keratolytic, a type of topical therapy that is used to soften keratin, a major component of the skin, which causes the outer layer of the skin to loosen and shed, leading to deeper skin absorption of topical treatment and other cosmetic ingredients. Salicylic acid leads to skin thinning to facilitate ingredient absorption into the deeper layers of the skin, whereas other BHAs and AHAs help stimulate the synthesis of dermis components and increase its thickness.
When used in its purest form, salicylic acid can be found in varying concentrations usually between 0.5-2%.
Consider some of the following salicylic acid skincare products to add to your routine:
- Paula’s Choice Skin Perfecting 2% BHA Liquid Exfoliant
- MURAD Clarifying Cleanser 200 ml
Other BHAs include beta hydroxybutanoic acid, tropic acid, and trethocanic acid, and some versions of citric acid that are classified as a BHA in cosmetic formulations.
BHAs are generally designed for daily use, but you may need to first patch test your BHA-containing product on a small area of your skin, and apply it once a week initially until your skin gets accustomed to it. Then increase it to a few more times per week as recommended by the cosmetic product manufacturer. As with AHAs, always apply sunscreen daily every two hours to protect your skin from harmful UV rays.
Polyhydroxy Acids (PHAs)
In light of their larger molecular structure, Polyhydroxy acids (PHAs) provide similar effects as AHAs without causing the skin irritation responses that tend to sometimes limit the use of traditional AHAs. The most common PHAs are gluconolactone, galactose, and lactobionic acid.
Studies have found PHAs to be compatible with clinically sensitive skin, including rosacea and atopic dermatitis. In clinical studies, PHA-containing products were also shown to work well with skin of colour, including darker skins.
PHAs such as gluconolactone or lactobionic acid may also be used in conjunction with other products, ingredients, or dermatological procedures such as laser and microdermabrasion to provide additional benefits to treatment or to enhance the therapeutic effect.
Additionally, most PHAs possess antioxidant, additional humectant and moisturisation properties compared with AHAs and can enhance stratum corneum barrier function, therefore increasing the skin’s resistance to chemical challenge.
PHAs such as lactobionic acid combined with AHA lactic acid, BHA and vitamin C could be found in these high-performing products:
- The Organic Pharmacy Enzyme Peel Mask with Vitamin C and Papaya
- Glossier Solution Exfoliating Skin Perfector
Can you combine AHAs, BHAs, and PHAs in your skincare routine?
Yes, you can combine products containing AHAs, BHAs, and PHAs in your skincare routine. Many skincare brands clevely combine these different acid groups at different concentration levels in their cosmetic formulations.
The main thing to remember though is that the higher the concentration and lower the pH of your chemical exfoliant, the more intense the exfoliative effect. Consequently, less is definitely more when it comes to this type of skincare.
Over-exfoliation can lead to skin irritation such as inflammation and dryness, sometimes accompanied by breakouts and skin peeling.
Ideally, stick to one type of chemical exfoliant based on your skin type and skincare concerns. If you need to combine different types of acid formulations for your skin needs, separate two products between your daytime and nighttime routines, and use the third one for the occasional weekly or monthly use, depending on targeted treatment.
For example, people with combination skin might need BHA-containing products to treat acne and AHAs to support skin hydration in drier areas, but the use of both acids if relying on two separate formulas ought to be split between morning and evening skincare routines. Alternatively, you can opt for a product combining both BHA and AHA or the three acid groups AHAs, BHAs and PHAs such as the Glossier Solution.
Whichever acid you decide to use, start off slowly. If you experience skin irritation or prolonged stinging, stop using the product and consult your dermatologist.
- As a rule of thumb, avoid using salicylic acid with any other acid at the same time, because this may trigger severe skin irritation when blended.
- Don’t use salicylic acid with niacinamide-containing products.
- Avoid using lactic acid or glycolic acid together with ascorbic acid (vitamin C), because this combination might negate all ascorbic acid’s benefits for your skin.
- Don’t use AHAs with retinol at the same time. Separate them between your daytime and nighttime skincare routines.
- If acid-based chemical exfoliation is far too strong for you, try the Non-Acid Acid Precursor 15% (NAAP) from DECIEM as a non-acidic alternative to acid-based epidermal resurfacing
Alpha Hydroxy Acids
Beta Hydroxy Acids
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Grimes PE, et al. (2004). The use of polyhydroxy acids (PHAs) in photoaged skin.
Sharad J. (2013). Glycolic acid peel therapy – a current review. DOI:
Mayo Clinic Staff. (2013). Skin resurfacing options that smooth facial wrinkles.
Mayo Clinic Staff. (2015). Over-the-counter acne products: What works and why.
Smith WP. (1996). Comparative effectiveness of alpha-hydroxy acids on skin properties.
SCCNF 0799/04 – Updated position paper concerning consumer Safety of alpha-hydroxy acids
Green BA, et al. (2009). Clinical and cosmeceutical uses of hydroxyacids. DOI:
Alexis AF, et al. (2013). Natural ingredients for darker skin types: Growing options for hyperpigmentation.
Kornhauser A, et al. (2009). The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin. DOI:
This blog post is not intended to provide diagnosis, treatment, or medical advice in any form or shape. Content provided on this platform is strictly for informational purposes only. This is based on my own research and reading of clinical studies in the beauty industry, keeping updated about new changes in the cosmetics market, and my personal journey of battling for over 25 years with severe skin disorders such as acne, eczema, and hyperpigmentation. Please consult with a physician or other healthcare professional regarding any medical or health-related diagnosis or treatment options you might have. Information on this platform should not be considered as a substitute for advice from a healthcare professional. The statements made about specific products throughout this video are not to diagnose, treat, cure, or prevent disease.