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A Guide to Chemical Exfoliating with AHA & BHAs

Different chemical exfoliants hold unique skincare properties. Read about AHA & BHA exfoliating acids & understand how their uses can visibly improve your skin.

Exfoliation plays a key part in any effective skincare routine due to its ability to revive, renew and enhance skin’s healthy appearance by removing dead skin cells. It achieves these results by breaking down the ‘glue’ that holds dead and damaged skin cells together which allows them to gently slough away. This removal of the upper layer of the epidermis provides an opportunity for new skin cells to emerge which in turn promotes healthy, rejuvenated looking skin.

There are two types of exfoliants; chemical and physical. Physical exfoliants are formulated with a coarse texture to manually buff away dead skin, whereas chemical exfoliants contain acids or enzymes that dissolve and loosen dead skin cells. Chemical exfoliants have been adopted by the skincare industry for over 40 years without being abrasive or rough to the outer layer of skin.1 Most chemical exfoliating skincare products used within the industry derive from either alpha-hydroxy acids (AHAs) or beta-hydroxy acids (BHAs), both of which are types of hydroxy acids. Understanding the types of ingredients used in chemical exfoliants for the face will help to address your individual skincare needs.

What's The Difference Between AHA and BHA Chemical Exfoliants? (1)

Alpha-hydroxy acids and beta-hydroxy acids are the two primary classes of hydroxy acids used in skincare. AHAs are water-soluble chemical exfoliating acids that stimulate the shedding of upper epidermal cells. Alpha-hydroxy acids can work to address skin concerns like scarring, pigmentation, dryness, wrinkles and acne-prone skin by breaking down the outer layer of the skin. This purposeful disruption encourages old and damaged cells to shed, revealing new, rejuvenated cells on the skin’s surface. Beta-hydroxy acids work similarly to AHAs, however, they are lipid-soluble and break down in oil. This compound structure allows BHA exfoliants to penetrate the skin’s pores, rather than just the skin’s surface like AHAs2, making BHA chemical exfoliants ideal for oily skin types and those with enlarged and clogged pores. Beta-hydroxy acids also have a lower skin-irritancy effect in comparison to AHA exfoliators, making BHAs more compatible for people prone to skin sensitivity. Both AHAs and BHAs can help address signs of ageing and encourage healthy skin cell turnover.

Why Hydroxy Acids are Ideal Exfoliators

With a vast range of skincare ingredients promoting skin health, what sets hydroxy acids apart from the pack can often be misunderstood. Despite all working to repair skin damage, when we compare AHAs and BHAs to retinol (a vitamin A derivative), it is important to note that retinol does not encourage the breakdown of dead skin cells. Both AHA and BHA’s primary function is to loosen the bond between cells, allowing for healthier skin appearance. This feature makes for an effective chemical exfoliation and highlights the importance of implementing hydroxy acids into your skincare regimen.

Key Types of Hydroxy Acids

Derived from natural plant species, hydroxy acids hold unique skincare benefits. By understanding the different properties of various chemical exfoliants, you can incorporate the right ingredient into your skincare routine in order to achieve optimal results.

Glycolic Acid

Naturally found in sugar cane, glycolic acid is the most common type of AHA chemical exfoliant. Glycolic acid was the first AHA compound introduced to skincare and is used to visibly clear skin, paving the way for brighter, healthier and stronger skin cells.3 The ideal glycolic acid concentration is 4%-10% and should be formulated with low pH for the strongest results. Incorporating the SkinCeuticals Glycolic 10 Renew Overnight into your evening skincare routine will stimulate cell turnover for visibly brighter and healthier skin. This night cream is suitable for oily, combination and dry skin types and can improve ageing and discoloured skin. 

Unique benefits of glycolic acid:
• Repairs damaged skin
• Treats signs of ageing

Lactic Acid

Lactic acid is a widely used AHA exfoliating chemical found in skincare products. Originally sourced from milk, lactic acid is used to treat signs of photoaging and reduces pigmentation on the skin. Lactic acid is an effective exfoliant as it promotes cell turnover, and unlike many acids it also contains moisturising properties. A chemical exfoliant formulated with lactic acid will remove dead cells whilst simultaneously helping to maintain moisture levels in the skin. (4) (5)

Unique benefits of lactic acid:
• Minimises signs of pigmentation
• Holds moisturising properties

Citric Acid

Known for its reparative abilities, citric acid is classified as both an AHA and BHA exfoliant. Derived from fruits, citric acid is effective at targeting rough or dry patches on the skin and reducing signs of ageing. Its ability to neutralise the skin makes it an ideal ingredient for toners and exfoliants, underpinning its recommended use by topical application. (3) (6) (7) The SkinCeuticals Blemish + Age Defense contains 0.5% citric acid to reduce the appearance of fine lines and wrinkles, smoothing and balancing the skin. 

Unique benefits of citric acid:
• Smoothes uneven skin
• Reduces signs of ageing

Salicylic Acid

Salicylic acid is a BHA exfoliant that is naturally found in the bark of willow trees. It encourages cell turnover by loosening the bond between cells, making it a key ingredient for many chemical exfoliants. Salicylic acid is a fat-soluble molecule with anti-inflammatory properties which makes it ideal for use on oily skin types, in addition to an effective treatment for acne. 

Unique benefits of salicylic acid:
• Suitable for acne-prone skin
• Gentle exfoliating properties

How to Choose the Right Exfoliating Acid for your Skin

Incorporating a chemical exfoliant into your skincare routine will allow for a healthy skin cell turnover. Both AHAs and BHAs make effective ingredients for chemical exfoliators, serums, toners and masks, with their ability to remove damaged or dead skin and encourage the production of new skin cells. Understanding the nuances of each hydroxy acid will work to achieve the best possible results for your skin as you can develop a tailored approach by understanding your individual skincare needs.

All AHAs and BHAs can cause UV sensitivity after topical application, so be sure to apply these in conjunction with high SPF protection. (3) (8)



Skin Ceuticals

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