Exfoliation with a Difference | Ultimate Guide to AHA, BHA, PHAs

Dermatologists have been using chemical peels for decades – a light acid to help remove outer, damaged layers of skin to help new skin grow underneath. They’ve used it to treat acne, dark spots, uneven skin and scarring for a long time with carefully documented safety guidelines and doses. The addition of such exfoliating acids to everyday skincare was a genius move in Korean beauty – bringing the ability of dermatologists into the hands of everyday people. Instead of separating AHAs/BHAs into a separate skincare treatment – K-Beauty brands integrated them into hydrating and soothing formulas, allowing for gentle pore care with minimal irritation. It’s about gentle and skincare in balance; delicately helping to refresh skin, whilst also infusing healing extracts and hydrating ingredients. It’s no wonder that AHAs and other exfoliating acids have become a darling of skincare – and are found in almost all acne/oily skin/aging treatments. But... what’s the difference between the different letters? When should you use each one?  

In a nutshell: AHAs are best for remodeling and removing rough, dry skin. There’s a wide variety of them, from glycolic acid (from sugar cane) to lactic acid (from milk), mandelic acid (from almonds), citric acid, and more. They are traditionally extracted from fruits and help give a brighter, more youthful appearance. They are used to help soften surface skin, help remove dead skin cells and refresh skin underneath – making them useful in dry skin, acne and anywhere you are struggling with uneven skin tone. 

Glycolic acid is the most commonly used in skincare – due to it’s small size; which allows deep pore penetration and cleansing. It can be the most irritating however, making it less beneficial for sensitive or easily irritated skin. 

Mandelic acid, however, is larger and gentler. It’s happy to sit gently on the surface of the skin and eat away dead skin cells – making it more beneficial for sensitive skin, while still giving the benefits of exfoliation. 

How to Use AHAs? 
AHAs should be used at nighttime as part of your cleansing routine before bed. This prevents you having irritation or redness during the day but also lets you re-hydrate your skin well before bed. A great cleansing routine, AHA product and soothing moisturizer is the secret to waking with soft and balanced skin. 

In skincare, we take about BHAs and 95% of the time we’re looking at salicylic acid. Salicylic acid has been used in medicine for millennia, extracted from willow bark, which contains a rudimentary form of aspirin. It helps calm inflammation at a baseline, but (in its acid form) helps melt away dead skin cells and excess oil, to help balance skin. It’s also famous for its ability to penetrate deep into pores, which is greatly beneficial for acne. 

Salicylic acid is by far the most common BHA used for oily skin and acne care, due to its ability to soothe redness and inflammation. It can be drying, so it’s only recommended for oily skin types (especially in stronger concentrations). 

Succinic acid is a soothing acid that similarly calms redness, whilst helping to tackle whiteheads, blackheads and inflamed regions of skin with quick results. When paired with hyaluronic acid, it helps boost extracellular matrix and skin firmness. 

How to Use BHAs? 
Use after cleansing and toning skin. BHAs make your skin more vulnerable to sun (as it’s removing dead skin cells away and leaves more youthful skin exposed), so it’s best to use in the evening routine and pair with a really good SPF+ protection during the day. Start with lower concentrations of BHA (high concentrations can cause dryness and irritation) and slowly build up. 

For good acne care, always use with mechanical exfoliation to clear away dead skin cells – either by massaging skin well or using a damp face towel to brush away debris. Follow with a nourishing, acne-safe moisturizer in the evening. 

PHAs are some of the gentlest and soothing exfoliating acids. They act similarly to AHAs (being great for smoothing skin, reducing fine lines and producing more youthful skin), but are larger so sit only on the surface. This reduces irritation and actually helps seal in moisture to your skin barrier; making them a great addition to balance and refresh sensitive skin. 

Gluconolactone is a rich antioxidant, helping to exfoliate but also hydrate in equal measure for gently transformed skin. 

Lactobionic acid is deeply hydrating molecule that provides more moisture than exfoliation action, but helps keep skin clear and balanced. 

How to Use PHAs? 
PHAs are best used in toners or serum (although there are some excellent cleansers that also use PHA to avoid stripping moisture from skin). This helps moisturize, whilst also removing dead skin cells for softer and clearer texture. Avoid using with lots of other AHAs/BHAs at once, which can over-exfoliate. It can be used in your morning/evening routine and has a limited risk of irritation. 

Unlike the other exfoliating acids, LHA is on its own as just one acid. It’s a derivative of salicylic acid, designed to be more gentle and with a similar pH to skin to avoid that drying effect of BHA. Similar to salicylic acid, it penetrates pores deeply to cleanse and refresh, whilst improving skin brightness. It’s a great addition to an acne routine – whilst being safe for sensitive skin types. 

How to Use LHAs? 

LHAs are used very similar to BHAs – part of cleansing and pore care to help relieve acne spots and large pores. It’s best used in your evening routine, followed by a good moisturizer and SPF+ protection for the morning.

Looking for a gentle exfoliation? We’ve got your back – with our top picks for exfoliation products for each skin type. Whether you’ve got dry skin, oily skin, fine lines or sensitive – there's a little exfoliation out there, just for you! 

Axis Y PHA Resurfacing Glow Peel 50ml 

Skin Type: Dry, Sensitive 
This peel is perfect for dry or sensitive skin, giving a deep hydration boost, whilst clearing flaky and uneven skin. It’s brightening with green papaya, green plum and cucumber and gives you a cool and refreshing skin treatment. Perfect for all skin types – but ideal for dry skin looking for a glowy boost. 

Mary&May Rice Glutathione LHA 200ml 

Skin Type: Fine Lines, Dry 
Looking for a refreshing cleansing oil? This fragrance-free oil is rich in LHA and rice extract, for a super brightening and refreshing effect. It’s designed for sensitive and oily/acne-prone skin as part of a double cleansing routine but can also be used for dry skin as a stand-alone cleanser to refresh the skin barrier. 

Heimish Rx AHA BHA Enzyme Scrub 130ml 

Skin Type: Oily, Acne 
This is a vibrant and refreshing scrub for oily skin – with the duo combination of AHA/BHA to balance both pore care and surface skin. Good for acne, oily skin for a deep cleansing action that helps balance sebum, reduce whiteheads and blemishes. 

Anua BHA 2% Gentle Exfoliating Toner 

Skin Type: Oily, Combination, Acne 
Refresh and clear pores, whilst providing a deep hydration with this brightening toner. With 2% BHA, it helps exfoliate away dead skin cells and clear pores, whilst infusing hydrating ceramides, hyaluronic acid and panthenol to moisturize and boost sensitive and oily skin. Perfect for acne and large pores. 

Haruharu Centella 3% PHA Gentle Liquid Exfoliating Serum 120ml 

Skin Type: Oily, Sensitive 
Vanish dull and dry skin with the power of gentle PHA blended with hydrating centella extract, blended with Anti-Sebum P and orange water for the glow of vitamin C. Perfect to balance skin that is too oily, but sensitive and requires gentle care. Helps vanish blackheads and oily zones, with a gentle formula. 

Axis Y LHA Peel & Fill Pore Balancing Cream 50ml 

Skin Type: Combination, Large Pores 
Smooth and hydrate skin with the power of LHA blended with centella asciatica, green tea extract and BHA to help hydrate and blur skin texture. Perfect to create a smooth canvas for make-up; whilst also improving pore health and hydrating skin. 

Balance and refresh your skin with the power of exfoliating acids. Perfect to refresh, balance sebum and boost hydration!

Looking for fresh, rejuvenating skincare for all skin types? Check out the range on Arktastic. Authentic K-Beauty sourced directly from Seoul.