A no-frills guide to understanding acids in skincare

Posted by
Lucy Partington

If there’s one sure way to revitalise your skin, it’s with the experts’ go-to: acids. But which ones do you really need?

Acids. They sound terrifying, especially when we link them to skincare (who can forget Samantha in Sex And The City and her acid peel – we’re mentally scarred for life) but they’re one of the biggest beauty buzzwords right now. And for good reason: cult brand Glossier has just dropped its first acid exfoliator called Solution, £19, to much hype and Alpha H’s iconic toner Liquid Gold, £33.50, now sells one every minute. 

Where they used to be a bit off limits – used only by skin obsessives, expert facialists and dermatologists – there’s been a huge surge in interest in acids across the skincare board. Indeed, Space NK has seen its sales of acids double in the past couple of years because of the demand for faster results and an increased consumer interest in skincare. And the reason for this excitement? Acids pretty much give instant (and cumulative) results.

“Acids work on superficial layers of skin, dissolving and breaking down the bond of dead skin cells to leave a fresh, even surface layer,” explains facialist Michaella Bolder

But not all acids are the same, she warns: “Retinoic acids work on a deeper level of the skin, speeding up cell turnover (and shouldn’t be used i combination with other acids), while L-Ascorbic acid – aka vitamin C – helps to protect the skin against free radicals and environmental pollution. That’s why you need to know what you’re using.”

Everything you need to know about acids in skincare

The increased popularity of acids has unfortunately come with issues of misuse. Dr Jules-Jaque Nabet, aesthetic doctor and medical director at Omniya, is seeing a growing number of people coming to his clinic after experiencing problems related to the overuse of acids. 

“People want instant results but aren’t following the proper instructions given in terms of how often to use an acid and which particular kind. Then they end up with sensitive skin that’s prone to sun damage and inflammation,” he says.

While overuse and potency (acids tend to come in percentage strengths) are tricky factors to navigate when you’re casting your eye across a crowded beauty hall, used correctly, acids are one of the biggest beauty game-changers – and a way to transform your skin. But knowing how to tell an AHA (alpha hydroxy acid) from a BHA (beta hydroxy acid) – the former is best for dry skin, while the latter suits normal to oily skin – and if a glycolic acid works best for your skin or if you’re ready for mega high-strength retinoic acid can be complex. 

Whether it’s brightening dull skin, softening fine lines or addressing pigmentation, scroll down to find out your perfect acid match – and the products you need to take your skincare game to the next level.

For pigmentation 

Use: Azelaic acid

What is it? “A naturally occurring dicarboxylic acid found in grains such as rye, wheat and barley,” says Dr Alexis Granite, consultant dermatologist at The Cadogan Clinic.

How does it work? It helps to reduce pigmentation by inhibiting an enzyme called tyrosinase, which is involved in the production of melanin – the pigment that gives skin its colour. It’s also antioxidant, anti-inflammatory and has antimicrobial properties that work well for mild rosacea and acne.

Can anybody use it? Yes: there’s little risk but lots of benefits. It doesn’t damage the skin barrier and it helps stop the growth of abnormal melanocytes (cells that form melanin) linked to melasma, which causes grey-brown patches, usually on the face. Actual skin saviour.

How should I use it? It is more gentle than other acids and likely to take longer to be effective, so be patient (use once a day on clean skin). Higher strengths – 15-20% – are available on prescription if pigmentation persists after six months.

Watch out for: It’s a mild exfoliant so can cause extra peeling – use with Aesop Elemental Barrier Cream, £39, which uses reparative agents to soothe the skin post-treatment.

The three azelaic acids below are our favourites for tackling pigmentation: 

1) Best for light pigmentation

Ren Ready Steady Glow Daily AHA Tonic, £25, contains azelaic acid, which brightens and gently evens skin-tone.

2) Best for sun damage

Sesderma Azelac Lotion, £18.20. Use this at night (it can cause light sensitivity) to help get rid of dead cells and combat redness.

3) Best for melasma

The Ordinary Azelaic Acid Suspension 10%, £5.50, is a highconcentrate azelaic acid (10%) in a lightweight gel-cream.

For deep exfoliation 

Use: Glycolic acid

What is it? The smallest molecule in the AHA family, so it’s easily absorbed by skin.

How does it work? “It fuels epidermal cell renewal, helping get rid of dead cells and stimulating new ones,” says dermatologist Dr Sandeep Cliff-Patel.

Can anybody use it? It’s not advisable if you use acne treatment Roaccutane. Those with sensitive skin should try polyhydroxy acid (PHA), which is good if your skin can’t tolerate AHAs: try Exuviance Soothing Toning Lotion, £26.

How should I use it? In your evening routine. It’s most effective when used regularly, but you need to build up tolerance, so go easy. Glycolic concentration of more than 20% is typically peel level (Sex And The City alert) and 15% is likely to irritate, so start low and work up. 

“A foaming wash is a great introduction as it’s not too strong,” Cliff-Patel adds. Or in the evenings, when your skin is in repair mode, try a cream or ready-soaked pad which stays on the skin longer.

Watch out for: A study found it can mildly increase sun sensitivity so use with Bobbi Brown SPF 50 Protective Face Base, £33, to nix this issue.

The three glycolic acids below will help buff your skin to perfection: 

1) Best for newbies

Nip + Fab Glycolic Cleansing Fix, £7.95. Its 2% glycolic acid gently retextures and exfoliates as it smooths the skin.

2) Best for regular use

NeoStrata Smooth Surface Daily Peel Pads, £46.99. With 10% glycolic acid, wipe over your face post-cleanse.

3) Best used monthly

Peter Thomas Roth Glycolic Acid 10% Moisturizer, £43.50. With glycolic acid and vitamin E.

For brightening 

Use: L-ascorbic acid

What is it? The active form of vitamin C is an antioxidant that protects skin from environmental damage, which can cause dull, crepe-like skin.

How does it work? Victoria Hiscock, production and education specialist at AlumierMD, says, “L-ascorbic has a natural effect on reducing excess pigment production, which leads to brighter and improve skintone.” Sign us up.

Can anybody use it? Yes: it’s one of the few ingredients backed by years of scientific research in which dermatologists and experts agree everyone should be using it.

How should I use it? Hiscock says it should be used in the morning to make the most of its antioxidant properties. It usually comes in serum or cream form: use the former directly on cleansed skin and the latter after your usual serum, because creams absorb more slowly into skin.

Watch out for: Water, or ‘aqua’, in the ingredients list. L-ascorbic acid is hydrophilic (water-soluble), and therefore dissolves in water. It’s also inherently unstable and oxidises when exposed to air or light, so packaging shouldn’t be transparent. Be an acid detective.

These L-absorbic acids get our vote for brightening power: 

1) Best with make-up

AlumierMD Vitamin Rich Smoother (C&E), £67.50. 15% L-ascorbic acid and vitamin E brightens and revitalises skin.

2) Best for all skin types

Mary Kay TimeWise Vitamin C Activating Squares, £22. Each square’s a stabilised vitamin C derivative.

3) Best day and night

The Hero Project Vit C-30 Ultra Brightening Serum, £39. A powerful serum: 30% stabilised vitamin C.

For firming 

Use: retinoic acid, or vitamin A

What is it? A prescription-strength ingredient proven to prevent and fight visible signs of ageing. Non-prescription strength retinoic acid is called retinol.

How does it work? “Retinoic acid directly enters the centre of the skin cell,” says Dan Isaacs of Medik8. “It attaches to retinoic acid receptors and triggers a reaction that tells cells to regenerate quickly, resulting in collagen production.” With regular use, this leads to plumper, firmer skin.

Can anybody use it? Isaacs explains that because it speeds up cellular regeneration it prevents skin ageing in the same way it helps to correct it. “It’s alsorecommended for acne sufferersas it prevents dead cells clogging pores,” he says. Avoid if you’re pregnant or breast-feeding – no evidence suggests it’s harmful, but there’s also none to suggest it isn’t.

How should I use it? It’s suitable for nightly use (with a moisturiser but don’t mix with AHAs or BHAs), but introduce to your routine slowly. “Use a low strength – 0.3% at first. Then upgrade to 0.6%, eventually working up to 1%.”

Watch out for: Most retinoids aren’t photostable, which means they deactivate when exposed to UV rays. Hence the opaque packaging.

Try these retinoic and vitamin A acids if you want to firm your complexion:  

1) Best for first timers

La Roche-Posay Redermic R UV SPF30, £30. Fragrance-free and non-poreblocking, this is even suitable for sensitive skin.

2) Best for mid-level

Medik8 Retinol Serum 6 TR, £39. This is developed with time-release technology to help lower the risk of irritation.

3) Best for experts

Paula’s Choice Clinical 1% Retinol, £53. Use three times a week at first then gradually increase frequency.

Images: Jade Rousseau / Avi Richards / Unsplash 


Share this article


Lucy Partington

Lucy Partington is Stylist’s beauty editor. She’s obsessed with all things skincare, collecting eyeshadow palettes that she’ll probably never use, and is constantly on the hunt for the ultimate glowy foundation.

Other people read

More from Beauty

More from Lucy Partington