What is glycolic acid? Everything you need to know

Medically reviewed words Annie Hayes, Dr Roger Henderson
Photo credit: Westend61 - Getty Images

From Netdoctor

Hailed as a miracle ingredient, glycolic acid has earned its reputation as one of the most versatile skincare acids around. Used for everything from acne to ageing, this potent chemical exfoliant tackles dead cells on the skin's surface to reveal a brighter complexion, minimise the appearance of pores and remedy uneven skin tone.

Beauty experts tout glycolic acid as an all-in-one solution skincare solution. But what actually is it? We asked skincare experts to explain the benefits of glycolic acid, discuss the various ways you can add it into your routine, and reveal how to incorporate it safely.

What is glycolic acid?

There are two common types of skincare acids: Alpha Hydroxy Acids (AHAs), which work by removing dead cells on the surface of your skin – also referred to as ‘resurfacing’ – and Beta Hydroxy Acids (BHAs), which penetrate deep into pores. Glycolic acid is an AHA.

‘Of the AHAs, glycolic is the simplest in structure and the smallest,’ says Dr Rekha Tailor, cosmetic doctor and skin specialist at Health and Aesthetics Clinic. ‘It has the lowest molecular weight, which means that it can easily permeate the skin. Glycolic acid exfoliates the outermost dead layer of the dermis and increases luminosity by improving the reflection of light on the skin.’

Originally derived from sugar or sugar cane, glycolic acid is usually made in a lab because it’s simple to synthesise. Chemical production is much cheaper than looking for natural sources, explains Dr Preema Vig, aesthetic doctor, former GP and owner of Dr Preema London Clinic. It’s available in a variety of concentrations, ranging from one per cent to 20 per cent.

‘It can be used in a home product usually at the lower concentrations, or a professional product used in an aesthetic practice at greatly varying concentrations,’ says Dr Vig. ‘AHAs, with their resurfacing activity, have a wide range of skincare applications, ranging from anti-ageing to acne and any other condition benefitting from resurfacing.’


Glycolic acid skin benefits

The main function of glycolic acid is to exfoliate the skin and break down dead skin cells. For this reason, it can be useful in treating acne, which occurs as a result of pores becoming clogged. Since the molecule is so small, it can penetrate the top layer of your skin (the epidermis) to act on the cells below – reducing the appearance of scarring and signs of premature ageing, including fine lines and wrinkles.

‘It also has antioxidant properties, and can help reduce pigmentation,’ says Dr David Jack, aesthetic doctor and skin specialist. ‘Glycolic acid, like other AHAs, also helps to reduce the pH of the skin surface, which can have beneficial effects on the skin microbiome – optimising the good bacterial flora on the skin surface.’

How to apply glycolic acid

Glycolic acid can be found in many different types of products, from home products to in-clinic peels. ‘It can be applied in creams, cleansers, toners or serums at weaker strengths, or in stronger forms as home peels – either as a fluid, in a masque form or on peel pads,’ Dr Jack explains. The latter generally need to be washed off, whereas serums and creams are usually left on the skin.

‘If you're just starting to incorporate glycolic acid into your skincare regimen, I would suggest using a gentle glycolic cleanser to get your skin used to it, rather than diving straight into a leave-on glycolic product,’ suggests Dr Tailor. ‘Glycolic acid is most effective when administered as a chemical peel by your cosmetic doctor – they utilise stronger ingredients for more potent effects.’

If using a serum or cream containing glycolic acid, apply it after cleansing in the morning. Glycolic acid leaves your skin vulnerable to sun damage, so always follow application with a high-quality SPF. ‘I usually suggest using a glycolic acid product intermittently rather than every day, as there is a small risk of skin irritation – particularly with very regular use,’ says Dr Jack.


Choosing the right glycolic acid for you

Firstly, look for products that contain ‘pharmaceutical grade’ ingredients, says Dr Vig, because the purity and effectiveness are verified by lab analysis. When it comes to the amount, quality trumps quantity.

‘Although we judge product efficacy on the percentage of glycolic acid in the product, modern formulating has moved away from that,’ she explains. ‘Due to scientific formulating advancements, higher percentages are not required to give a more dramatic result.’

This means a high-percentage glycolic acid product made with cheaper ingredients ‘will give much poorer results than a product made with lower-percentage pharmaceutical grade glycolic acid combined intelligently with other key ingredients’.

Photo credit: andresr - Getty Images

Generally speaking, you should look for a product that contains glycolic acid below 10% and with a pH of around five, says Dr Jack. ‘Higher strengths and lower pHs tend to need to be neutralised and have much higher risk of skin irritation,’ he explains.

‘I tend to prefer products that contain a blend of lower strength AHAs than a single high strength AHA as the risk of irritation and redness with glycolic acid is higher than some of the others,’ he continues. ‘A blend might include e.g. mandelic, lactic and glycolic acid.’

Whichever product you choose to use at home, be sure to patch test a small area of skin with the product first to make sure you don’t have an adverse reaction.


Glycolic acid side effects and dangers

On its own, it’s unlikely to cause a severe reaction. However, you should take care when using glycolic acid – or indeed any AHAs – with other skincare products, as it may potentially irritate the skin.

‘While glycolic acid can be beneficial in conjunction with other, gentler exfoliators like salicylic acid, when combined with stronger exfoliants like retinol, it can be too strong for most skin types,’ warns Dr Tailor. ‘Overall it's actually very safe – so much so that we can use this active ingredient during pregnancy.’

Another benefit of glycolic acid is that it is immediately neutralised upon contact with water, she continues. ‘Not only can you rinse it off if you feel tingling, but even if it penetrates deeply into your skin, it eventually reaches the water in the dermis. There it's neutralised and won't go any further.’

Be sure to apply sunscreen after daytime application. ‘Using an excellent sunscreen is an absolute must, otherwise sun damage will negate any gains made and cause further damage to your skin,’ adds Dr Vig. ‘Also, if the glycolic acid product is used too frequently it can lead to a thin, shiny, damaged epithelium, which gives that ‘over-processed’ look.’

Last medically reviewed on: 10-06-2020

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