All About Exfoliating Acids

When the words ‘exfoliating acid’ or ‘chemical’ comes to mind, many of us think of ingredients that are harmful for skin. But did you know there are actually plenty of safe chemical based skincare products which effectively exfoliate skin, and are often the most gentle alternative to physical exfoliators?

Hydroxy Acids (HA) are a rising star among Asian and Western skincare brands. Hydroxy Acids are favoured for promoting a healthy turnover cycle of skin cells, solving common skin textural issues and unclogging pores without depriving skin of essential moisture. We’re here to give you some insight into the differences between Hydroxy Acids (alpha hydroxy acids, or AHAs and beta hydroxy acids – BHAs) and some other upcoming exfoliating acids. 

Tip: Remember to follow up with moisturiser and sunscreen in the day time when using chemical exfoliants to avoid skin sensitivity.


AHA stands for Alpha Hydroxy Acids which are the most widely used form of HA, as they are easily accessible from vastly grown sugarcane and fruits. They’re water-soluble acids, meaning they can’t penetrate through the skin’s natural oils. For this reason, they’re mostly used for their exfoliating properties on the skin's surface, by lifting off the build-up of dead cells on the skin's surface to reveal a brighter, smoother complexion. They’re great for evening out skin tone, improving hyper-pigmentation and reducing the appearance of wrinkles. Some AHAs also will attract hydration to the skin, making them ideal for dry and aging skin. Some of the most popular choices of AHA are:

  • Glycolic acid -a popular form of AHAs, used in small concentrations of 1-2% to act as a mild exfoliating agent in face washes intended for daily use. When used in toners/serums/ampoules the concentration is higher, and should therefore be used less frequently (twice weekly at most) to avoid skin irritation. 
  • Lactic acid - is just as powerful as Glycolic acid, but milder in the sense that it’s typically best for sensitive skin types which have negatively reacted to another AHA in the past. It’s mainly used in products for unifying skin pigmentation. 
  • Malic acid - the go-to for acne-prone skin. It does more than just focus on removing a buildup of dead skin cells, it can reduce the formation of acne bumps (often referred to as ‘bumpy skin’).
  • Mandelic acid - recommended for sensitive and acne-prone skin types as an alternative to glycolic acid. Mandelic acid has a larger molecular structure which doesn’t penetrate skin as deeply glycolic acid, meaning the likelihood of causing skin sensitivity is lower. It is helpful for fighting the inflammation of acne and minor hyperpigmentation issues associated with acneic skin.
  • Citric acid – also works at exfoliating the upper layer of skin to reveal a smoother and brightener skin complexion, but additionally supplies protective antioxidants which help overcome skin damage caused by environmental aggressors.


BHA stands for Beta Hydroxy Acids which are oil soluble organic carboxylic acids, meaning they have the ability to penetrate deeper into pores, to clean out and dissolve excess sebum build-up. For these reasons BHA products are highly recommended for oily/combination skin types, breakouts and blackheads as they thoroughly clean out pores to avoid the accumulation of acne causing bacteria. Types of BHA you’re likely to find in your skincare products are:

  • Salicylic Acid – found in most cleansers, pore cleansing toners and exfoliating toner pads aimed at oily and acne-prone skin. It draws out dead skin cells and other impurities embedded within pores to reduce blackheads and whiteheads.
  • Betaine Salicylate – takes on similar qualities as Salicylic acid, but is the weakest BHA. Again, it is used for deterring mild forms of acne. 
  • Salix alba or Willow Bark Extract – a multifunctional ingredient composed of Salicin. It’s used as an anti-inflammatory, antibacterial and alleviates acne. It also provides potent skin soothing qualities.


LHA stands for Lipohydroxy Acids which are a derivative of Salicylic acid, and are therefore described as new generation BHA. LHA are more fat soluble than BHA and so they work more slowly. They can be used in leave-on products to work overtime. 


PHA stands for Poly-hydroxy Acids which are a new generation of hydroxy acids. They still serve as exfoliators at the surface of skin, means that they penetrate more slowly, but pose less of a chance of inflicting irritation on skin than AHA as they attract water to help the recovery of skin. If use of AHA or BHA have led to sensitising your skin barrier in the past, or you have dry/sensitive skin, PHA is a good option for you. Here are some types of PHA:

  • Gluconolactone – a chemical exfoliant and humectant which hydrates whilst buffing away dead skin cells.
  • Galactose – an all-in-one ingredient which polishes the outer layer of skin, counteracts the effects of overexposure to free radicals and hydrates skin.
  • Lactbionic acid – a hybrid of gluconic acid and galactose usually formed by oxidizing lactose. 


Other notable chemical exfoliating ingredients

Azelaic Acid is well recognised for its impact on fading pigmentation concerns associated with acne and other blemishes. However, in leaves on treatments/creams it refines skin texture and decongests pores through antioxidant activity.


How to begin

When using any type of chemical exfoliating product, the golden rule is to start low and slow. If your skin is sensitive, you should patch test a product first, like applying a small amount behind your ear, and seeing how your skin reacts after 24 hours. No matter which hydroxy acid you use, it's best to start low and work your way up, because if you use an acid too frequently or use a concentration that is too high, your skin may become irritated or inflamed.

Tip: If you have dry skin or skin that has been damaged by the sun, try an AHA. If you have oily skin or skin suffering from spots or blackheads, look to BHAs. If your skin is more sensitive, PHAs are great to start with.


AHAs are ideal for dry skin and those with aging concerns

According to expert Cindy Kim, co-founder of Silver Mirror Facial Bar,  AHAs are most effective at concentration of 8-10 percent, and have a maximum concentration between 10 and 15 percent. If you're new to AHAs, start with a concentration lower than 8 percent. 


Exfoliating AHA acid, COSRX AHA 7 Whitehead Power Liquid


Cosrx AHA 7 Whitehead Power Liquid is formulated with 7% Glycolic Acid (AHA) gently exfoliates skin and helps reveal a radiant even-toned complexion.


BHAs are better for Oily skin and congested pores

BHA concentrations can range between 0.5 and 5 percent, and BHAs are most effective at concentrations of 1 to 2 percent. If you're new to BHAs or have occasional breakouts, 1-percent BHAs are good to start with. 


Exfoliating acid, COSRX BHA Blackhead Power Liquid


Cosrx BHA Blackhead Power Liquid  is a chemical exfoliation liquid that penetrates deeply into the pores and helps clear clogged pores and gently exfoliates dead skin cells with 4% natural BHA. It leaves skin feeling refreshed and renewed. Recommend to use 2-3 times in a week, and gradually build up the usage according to the skin condition.


PHAs are ideal for sensitive skin

Even though PHAs are gentle and non-irritating, you should always start slow when incorporating them into your routine. 


Exfoliating acid PHA for sensitive skin, Banobagi Calming Care Moisture Pad


If you're interested in giving PHAs a try, the Banobagi Calming Care Moisture Pad  is great product to start with, to remove dead skin cells and clear your clogged pores while calming skin to reduce irritation. This gentle moisture pad is designed for daily use as the acid concentration is very low. We love these pads because they're made with 100% natural cotton wool sheet which are super soft and gentle. 

If you're looking for an acid exfoliant to target more skin concerns, SOME BY MI AHA-BHA-PHA 30Days Miracle Toner is a multi-tasking exfoliating toner for all skin types. As its name suggests, this miracle toner infused with three types of hydroxy acids (AHAs, BHAs and PHAs) to gently exfoliate skin and keep skin smooth and healthy.


Don't forget your SPF

Even though it's essential to wear sunscreen daily, but if you incorporate an acid into your skincare routine like AHAs which exfoliating effects make your skin more sensitive to the sun, for this reason wearing sunscreen every morning is a must to prevent skin damage. Try to use your AHA nighttime only. 


How to use exfoliating acids correctly

It's best to apply your AHA or BHA exfoliant right after cleansing and toning steps as they need to be absorbed into the skin to work. If it's a liquid, apply it with a cotton pad. 

You don't need to wait for the hydroxy acid to dry, you can immediately apply other products in your routine afterwards- serum, eye cream, moisturiser or sleeping mask. 







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