#SkinSchool: Everything you really need to know about glycolic acid (2022)

Take a glance at the bottles on your skincare shelf: chances are, at least one of them contains glycolic acid. Perhaps it features in two, three, or more of your go-to formulas.

But, as with all things in skincare, more is not always more. While the exfoliating, brightening, pigment-fading powers of this hard-working resurfacing compound are indeed formidable, incorrect or overzealous use of glycolic acid can wreak havoc with your skin barrier, which is there for good reason.

Here, we break down everything you should know about glycolic acid: how it actually works, what the benefits are, and the products that harness its brightening, resurfacing properties best.

What is glycolic acid?

“Glycolic acid is a chemical exfoliating ingredient that is derived from sugar cane. It is part of the alpha hydroxy acid (AHA) family, which also includes other well-known ingredients, such as lactic acid,” explains Dr. Anita Sturnham, a GP specialising in dermatology and founder of skincare line Decree.

Glycolic acid has the smallest molecules of all AHAs, enabling it to effectively penetrate the upper layers of the skin.

What does glycolic acid do?

Glycolic acid, like other AHAs, acts on the surface layer of the skin to dissolve the ‘cement’ between dead cells. It therefore gently resurfaces skin without the need for scrubbing. This is why acid-based products are often referred to as ‘chemical exfoliators’, in contrast to traditional, grit-based ‘physical exfoliators’, which are now largely regarded as the inferior, outdated option due to their abrasive nature.

“AHAs are water soluble, so they work well on the superficial skin layers, which we call the epidermis,” explains Dr. Sturnham. “Glycolic acid has been shown in studies to have dermal influence, boosting collagen-remodelling cells (which helps to reduce the appearance of fine lines and wrinkles), and melanocyte-stabilising properties, meaning it works well for pigmentation, too. It’s a versatile multi-tasker.”

“The process works by loosening and dissolving the glue-like substance called the desmosome, which holds old skin cells together,” explains Dr. Sturnham. “As they get to work, you often feel a tingle in the skin. Once the desmosome is broken down, the skin naturally sheds its old, dead skin cells. So, although you won’t actually see your skin exfoliating, you’ll soon see and feel the smoother textured, more radiant-looking skin.”

How much is too much?

Where skincare acids were once approached with caution – especially outside of the safe confines of a clinic – it seems we’re now happy to experiment with different acid-based products. However, good results only come from educated use.

According to Dr. Sturnham, the trend for ‘over exfoliation’ is currently a big issue. “Many of the skin conditions that I see and treat in the clinic are self-inflicted because of this. So many people are obliterating their skin barriers with exfoliating cleansers, followed by exfoliating acid toners, acid serums, beads, grains and scrubs in an attempt to create a flawless skin tone, but sadly this type of product strategy tends to make skin worse,” she warns.

In the EU, the amount of ‘active acid’ permissible in a home-use product is 10 per cent. “Anything claiming to have higher levels is likely to be buffered with an alkaline agent, which is quite misleading. Sometimes these are buffered to a level that leaves hardly any active acid at all,” says Dr. Sturnham. “Other skin-stimulating ingredients are added instead, such as menthol or peppermint, to make the skin tingle, so you feel like you are getting an acid exfoliation. 10 per cent is still a punchy dose, so you only need to do a deep working acid treatment once a week.”

The skincare industry has clearly picked up on our ill-advised appetite for super-strength exfoliators, with countless glycolic-based products promising mega strength, with the implication that this will lead to equally mega results. However, when finding the best glycolic acid product for your skin, it’s not purely about the percentage of acid inside.

As Dr. Sturnham explains, the pH of the finished product plays just as important a role in determining its strength. “In terms of choosing your acid dose for your once weekly treatment, the higher the concentration of acid and the lower the pH, the faster the keratolytic effect, meaning that the desmosome glue will break down quicker, speeding up shedding of old dead skin.”

To make matters more complex, another important factor is the Pka of the product, which the majority of brands don’t declare. “Pka is more specific and tells you the PH that the molecule needs to be to accept or donate a proton. The lower the Pka, the stronger the acid. I expect we will see this measurement included on products more and more over time.”

How to use glycolic acid correctly

So it seems the message is clear: when it comes to using glycolic acid products at home, less is more.

Dr. Sturnham recommends using a gentle, low dose of exfoliating acid every evening; she suggests an AHA cleanser, although a glycolic acid toner also works well. If you prefer a more active treatment, such as a mask or pad, restrict it to once weekly.

What’s more, if you’re opting for a high-strength glycolic acid product, it’s crucial to replenish the skin after exfoliation – a factor that many brands don’t consider. “I believe that no strong exfoliation of the skin should be performed without an accompanying mask that puts back moisture and conditioning actives into the skin,” says Dr. Sturnham, whose own Weekly Decree treatment comprises an exfoliating fruit-acid gel as well as a lipid-rich replenishing cream.

Finally, a leave-on serum can be a great way to reap the benefits of glycolic acid. Many can be used nightly, but if you're new to resurfacing products or have sensitive skin, it pays to proceed with caution. Try incorporating your chosen product into your routine once a week to monitor how your skin reacts, and always use an SPF in the daytime (as acids can increase skin sensitivity to sunlight).

Here, see the 16 best glycolic acid products the Bazaar team trusts, from a cult toner to pro-level peels for dark spots, and a couple of winning formulations that triumphed during forensic Bazaar Lab testing.

The best glycolic acid products to try now

The glycolic acid cleanser

ExfoliKate Cleanser Daily Foaming Wash

Cult Beauty

Kate Somervillecultbeauty.co.uk

£34.00

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A glycolic acid cleanser makes a good introduction to exfoliating acids, as the contact time with the skin is shorter than with a serum or cream.

Kate Somerville's lightly foaming cream cleanser contains glycolic alongside lactic acid and fruit enzymes, so works well on surface dullness and congestion. Introduce it into your routine a few evenings a week, and always wear a facial SPF by day.

The daily glycolic acid toner

Glow Tonic

Boots

Pixiboots.com

£18.00

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A resurfacing toner is an easy way to reap the brightening benefits of glycolic acid: simply swipe over skin with a cotton pad after cleansing.

Pixi's cult classic isn't just a hit with beauty editors: it impressed during Bazaar Lab testing too. A top performer, it helped improve the panel's skin texture and minimised the appearance of pores. Although some would have preferred it to be more hydrating, it did leave testers with brighter skin – and no uncomfortable dryness.

A moderate-strength solution, this one is suitable for almost all skin types, and can be used as your nightly low-dose treatment. Acid beginners, start here.

The high-strength glycolic acid toner

Liquid Gold

Lookfantastic

Alpha-Hlookfantastic.com

£39.95

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Alpha H found fame by formulating glycolic acid-based resurfacing products, and the brand is still a go-to for effective options. The original (and frankly, legendary) Liquid Gold is a toner-style treatment that combines glycolic acid with liquorice to bolster the brightening effects, meaning it works especially well on pigmentation.

A low pH and high acid percentage combine to make this one a stronger option for seasoned users. The brand recommends using only every other evening – for those new to acids, limit to a once-weekly application to begin with.

The glycolic acid overnight treatment

Sleep Glycolic Serum

Lookfantastic

Medik8lookfantastic.com

£35.00

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Medik8's brand-new glycolic acid product is designed to mimic the effects of a brightening in-clinic peel. With a pH of 3.5, it contains a potent 10 per cent concentration of AHA, encapsulated to ensure gradual release into the skin, thus reducing any risk of irritation. This is a fantastic option for anyone that has built up a tolerance to glycolic acid, but don't exceed the recommended two-to-three applications per week.

The glycolic acid pads

Alpha Beta Ultra Gentle Daily Peel

Dr Dennis Grossspacenk.com

£89.00

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These are the peel pads that started it all: loved by beauty insiders the world over, Dr. Dennis Gross’ Alpha Beta Peel sachets make light work of exfoliating dull skin. They now come in three degrees of strength, so you can work your way up to the level that most suits you.

However, we recommend starting with the Ultra Gentle iteration, whether you consider your skin to be sensitive or not. Simply swipe over cleansed skin to let the blend of five acids dissolve skin-clogging debris, then neutralise any lingering acid with the soothing second step.

The glycolic acid peel

Vinoperfect Glycolic Peel Mask

Lookfantastic

Caudalielookfantastic.com

£20.40

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Glycolic and lactic acids combine with a potent brightening antioxidant in this rich and creamy mask. Working to refresh skin in just ten minutes, it's a great pick-me-up to call on before an event.

The glycolic acid moisturiser

Moisturizing Renewal Cream

Space NK

Revive

£140.00

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This powerhouse night cream is your one-and-done treatment for exfoliating, brightening and conditioning skin overnight. Glycolic acid is combined with the humectants and emollients required to replenish the skin barrier, ensuring a healthy, unified glow.

The glycolic acid essence

Soft Reset AHA Exfoliating Solution

Cult Beauty

SUMMER FRIDAYScultbeauty.co.uk

£49.00

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This one contains a soothing base of aloe vera and glycerin and is free from drying alcohols, meaning the high level of alpha-hydroxy-acids is more easily tolerated. That said, we wouldn't recommend it for an acid newcomer, or for the very sensitive.

There's also a heavy dose of niacinamide inside, which works especially well on breakouts. It's free from scent and the texture is almost serum-like: an impressive formulation for those acclimatised to acids.

The glycolic acid serum

Good Genes Glycolic Acid Treatment

Space NK

Sunday Rileyspacenk.com

£85.00

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Sunday Riley’s eponymous brand is one to trust when it comes to effective actives. This creamy resurfacing serum is one of her most widely loved, thanks to the way it works on a deeper level to dissolve debris and excess oil, leaving skin looking cumulatively brighter and unified.

When it comes to serums, your skin's tolerance to acids should determine how often you apply: a gentle tingle is ok, but a burning sensation is not. This one is fairly potent, so go slowly: a night or two per week should deliver optimal benefits.

The weekly glycolic acid treatment

Weekly Decree

The Decree

Decree£120

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Based on Dr. Anita Sturnham's belief that good acid treatments should replenish as well as exfoliate, this weekly mask involves two steps: a potent glycolic-steeped exfoliating gel and a creamy hydrating mask to replace the moisture and lipids that acids can strip from the skin. Make it your once-a-week evening treat.

Liberty London

QMS Medicosmeticslibertylondon.com

£78.00

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This wash-off treatment is a good choice for sensitive skin, as it isn’t left on for long. Apply the liquid to a cleansed face, leaving it to work for up to 10 minutes (less for highly sensitive skin), before removing with water and applying moisturiser.

The texture refiner

Kombucha + 11% AHA Exfoliation Power Toner

Cult Beauty

Youth To The PeopleCult Beauty

£33.00

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A brilliant choice for sloughing away dead skin cells, this watery multi-acid toner brightened all testers’ skin, with the majority seeing an improvement in smoothness and texture. When it came to the Bazaar Lab test, it scored a respectable 7/10 for its ability to reduce the look of brown spots, too.

The multi-acid mask

Glycol Lactic Radiance Renewal Mask

Space NK

REN Clean Skincarespacenk.com.uk

£36.00

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A weekly mask can be a great way to reap the benefits of glycolic acid and quickly refresh dull, congested skin. REN's long-loved gel formula swiftly addresses overly enlarged pores and blackheads, and even boasts a citrussy scent to deliver a touch of spa-style pampering. Apply it once weekly, for no more than ten minutes, and remove with a warm, damp flannel.

The glycolic acid scalp treatment

Glycolic Acid Exfoliating Scalp Scrub

Boots

The Inkey Listboots.com

£14.99

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Glycolic acid is a great ingredient to use on the scalp, as it'll help dislodge product build-up and excess oil from your roots. Use this weekly deep-treatment liquid to sweep away the week's residue, leaving hair full of volume and movement.

The glycolic acid body scrub

Body Peel

Feelunique

Verso Skincarefeelunique.com

£27.50

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Not just a great face exfoliator, glycolic acid is brilliantly effective on the body, too.

A step up from your usual body scrub, Verso's exfoliating peel works on both a physical and a chemical level, with glycolic and salicylic acids to resurface scaly elbows and clarify a congested back. It works brilliantly at removing lingering fake tan too.

The intensive all-in-one treatment

Resurfacing Compound

Space NK

U Beautyspacenk.com.uk

£138.00

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A maximalist choice, this watery gel-serum combines glycolic acid with vitamin C, peptides and hyaluronic acid to deliver a comprehensive skin-renewal treatment. It's potent, so steer clear if you're very sensitive, but for more mature skin types that want a powerful rejuvenator, this may well be it.

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