Acids Decoded: What Are AHAs, BHAs And PHAs In Skincare?

Want flawless skin? Acids are the answer.

Three models backstage at Edeline Lee, Fashion Week
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Acid - the very word is enough to trigger uncomfortable thoughts of sore, tingling skin for those who aren't in the beauty know.

And for those who are? Well, they know that incorporating acids into a regular skincare regime is the answer to a pretty much flawless complexion.

From Alpha Hydroxy Acids (AHAs) and Beta Hydroxy Acids (BHAs) to the new acids on the block for 2018, Polyhydroxy Acids (PHAs), these hard-working chemical exfoliants can minimise acne, erase pigmentation and blur fine lines - and that's just the tip of the iceberg.

The best part? You don't need a degree in chemistry to know how to use them, and thanks to brands like Glossier, Medik8 and The Ordinary, you won't be left with red raw cheeks, either.

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What Are AHAs In Skincare?

'AHAs are chemical exfoliators that can be extremely helpful for oily or blemish-prone skin if used on a regular basis,' says Dr. Anjali Mahto, consultant dermatologist and British Skin Foundation spokesperson.

The most common AHAs in skincare are Glycolic Acid and Lactic acid. These both work by dissolving the upper layer of dead skin cells to blur red marks left behind by acne, erase pesky patches of pigmentation, and, if you suffer with minor breakouts or bumpy, uneven skin texture, prevent spots from popping up with consistent use.

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What's the difference between Lactic Acid and Glycolic Acid?

Well, Glycolic Acid has a smaller molecular size than Lactic Acid, meaning it can penetrate the skin a little better.

Because of its slightly larger molecular size, Lactic Acid is a bit less irritating on the skin, but works in the same way - by sloughing off the top layer of skin cells to reveal fresher, brighter, plumper skin underneath. Both improve the skin's moisture levels, too.

Pro Tip: Acids come in varying strengths, so talk to a dermatologist if you're finding it tricky to determine the right percentage for your skin type.

The Ordinary Lactic Acid 10% HA 2%


- The Ordinary Lactic Acid 10% HA 2%, £5.80

Blast under-the-skin bumps and blocked pores with a nightly slathering of this stuff. Choose between either 5% or 10% Lactic Acid to turf sebum, grime and dead cells out of pores at record speed. The added hyaluronic acid prevents the skin from feeling tight and dehydrated.

- Nip & Fab Glycolic Fix Liquid Glow, £19.95

Model of the moment Sofia Richie recently put her glowing skin down to a swipe of this stuff and we can confirm it works a treat. Thanks to the 6% Glycolic Acid, blemishes will be banished with regular, nightly use and it doesn't sap skin of moisture.

- NeoStrata Foaming Glycolic Wash AHA 20, £25.99

Skin look like an oil slick come 3pm? Spots that won't let up? Bring out the big guns. This dermatologist-approved foam cleanser boasts a huge 18% Glycolic Acid to cut through sebum and to retexturise and resurface uneven skin. We swear by it.

NeoStrata Foaming Glycolic Wash

What Are BHAs In Skincare?

BHAs are also chemical exfoliators, but they're better catered to oilier skin types that are prone to acne, blackheads and milia, AKA those annoying little white bumps under your skin.

Why? Not only do they exfoliate the top layer of skin, but they can penetrate blocked pores by making their way into the oil glands, dissolving the paste-like mixture of sebum and dead skin that can lead to spots. The most popular BHA in skincare is Salicylic Acid.

'Exfoliating with a leave-on BHA that contains salicylic acid is a game-changer,' says Paula Begoun, skincare specialist and founder of Paula's Choice. 'It gets rid of dull cells but doesn't strip the skin's essential oils.'

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Salicylic Acid is also a proven anti-inflammatory, which means it's perfect for calming raging zits and reducing pigmentation or redness caused by acne.

Even better? Using AHAs and BHAs together delivers a double-pronged attack on stubborn skin concerns like acne, sun damage and clogged pores, exfoliating the skin more thoroughly. Simply alternate between an AHA product and a BHA product either each evening or weekly, or grab one that contains both.

Paula's Choice Skin Perfecting BHA Liquid Exfoliant


- Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant, £26

Blackheads don't stand a chance against this leave-on exfoliant. Make sure your skin is squeaky clean, decant a few drops onto a cotton pad and swipe. It doesn't tingle or feel sticky on skin.

- DCL Multi-Action Penta Peel, £58

A quick, nightly once-over with these Salicylic-soaked pads after cleansing results in fewer blackheads and a much less oily T-Zone. They don't count as liquid, which makes them travel-friendly, too.

- LIXIR Night Switch BHA/AHA, £20

With a dream-team of AHA Lactic Acid and BHA Salicylic Acid, this serum works in tandem with your skin cells as they regenerate overnight to leave you with fresher, more even-toned and textured skin in the morning. No wonder it has a huge beauty following already.

LIXIR Night Switch BHA/AHA Serum, Lixir Skincare

What Are PHAs In Skincare?

There's a new complexion-perfecting acid on the block for 2018 and it's a must-have for those with sensitive skin.

'PHAs (AKA Polyhydroxy Acids) are very similar to traditional alpha hydroxy acids, because both work by breaking down the 'glue' that binds dull, dead cells to the surface of the skin,' explains Daniel Issacs, Head of Formulation and Development at Medik8.

So what sets PHAs apart?

'Their difference lies within their molecular structure,' explains Daniel. 'The molecules that make up PHAs are much larger in size, which means they cannot penetrate skin as deeply as traditional AHAs and BHAs. Instead, they work exclusively on the skin's surface without disturbing the delicate layers that lie beneath. This ensures optimum skin renewal with minimal irritation.'

They're especially beneficial for those who find other acids too strong. 'Even very sensitive skin types can harness the resurfacing powers of PHAs,' says Daniel. 'In clinical studies, they have been proven to be compatible with dry, itchy skin conditions such as eczema and atopic rosacea.'

Glossier Solution Exfoliating Skin Perfector


- Glossier Solution, £19

With a mega-mix of AHAs, BHAs and PHAs, the newest addition to Glossier's skincare line promises clearer, more radiant skin - and boy, does it deliver. We'll take two more bottles, please.

- Medik8 White Balance Click Oxy-R, £59

PHA Glyconolctone is the star ingredient in this non-sticky serum. If spots leave you with stubborn, red, under-the-skin blemishes, you need it pronto.

- Zelens PHA+ Bio-Peel Resurfacing Facial Pads, £65

PHAs in Zelens' handy pads shed dull skin cells, stimulate collagen for skin that is plump and pillowy (see ya, fine lines) and minimise enlarged pores. If you find Glycolic Acid irritating, stockpile them.

Zelens PHA+ Mirco-Peel Pads

Remember To Always Apply An SPF When Using Acids

Whatever percentage, acids have a tendency to make skin sensitive to things like UVA, so slathering on the SPF during the day is paramount to keeping your glow.

'SPF is important if treatments are being applied to the skin that are causing exfoliation e.g. AHAs, BHAs,' says Dr. Anjali. 'The skin is more vulnerable to damage and pigmentation change following these types of treatments and pigmentation can potentially get worse if SPF is not applied.'


- Heliocare Advanced SPF 50 Gel, £19

Beloved by dermatologists all over the globe, this SPF is non-comedogenic, which means it won't cause any blockages.

- NIOD Survival 30, £25

This serves up mineral-only UVA and UVB protection and won't make your serum, moisturiser or foundation pill. Instead, it sits comfortably on the skin all day.

NIOD Survival 30 Mineral SPF
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