The definitive guide to different types of skincare acids

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  • Think you know your acids?

    These days you can barely talk about skincare for five minutes without acids coming up in conversation.

    Hyaluronic, malic, glycolic, salicylic – it feels like there is an infinite number of different acids for skin and so can feel hard to know which you should use.

    But, no more: allow us to give you a brief overview of the big hitters and the products containing them that you should use for your skin type. It’s not as complicated as you probably think (and that’s coming from someone who hated chemistry at school).

    Keep scrolling to find out the differences between the most commonly used skincare acids below.

    Salicylic acid

    Beta-hydroxy acid (BHA), also known as salicylic acid, is an exfoliant that penetrates deep into the skin’s layers, encouraging the pores to unclog.

    It’s able to break down the things that clog your pores, like dead skin cells, dirt and excess oil. As well as this, it’s also a great anti-inflammatory agent, which is why you’ll often find it in spot gels and acne treatments.

    Hyaluronic acid

    Often cited by skincare experts as the hydrating hero, hyaluronic acid is known for its incredible ability to hold over 1,000 times its own weight in water. A substance that’s naturally present in the body (particularly the eyes and joints), it’s also humectant, so draws moisturse to the skin from the environment.

    Hyaluronic acid serums are one of the most popular methods of hydrating the skin, and the plumping effect makes it a great anti-ager. It’s also used in non-permanent lip fillers.


    Citric acid

    You’ll recognise the name from your favourite fruits, but citric acid is also used in many skincare products for gentle exfoliation –  it’s why a lot of at-home face peels smell like oranges. Citric acid is also in the alpha-hydroxy acid group.

    Glycolic acid

    An alpha-hydroxy acid (AHA), glycolic acid is one of the two most popular chemical exfoliants used in peels and toners.

    ‘Glycolic acid is one of the smallest molecules of the alpha-hydroxy acid family, meaning it is water soluble and penetrates deeply into the skin,’ says Mark Curry, co-founder of The Inkey List. ‘Our Glycolic acid comes from sugar cane.’

    Sensitive skin types may find this one a bit irritating or harsh on the skin, so always introduce it into your regime gradually and in a small concentration first.

    Lactic acid

    ‘Lactic acid is one of the larger molecules of the alpha-hydroxy acid family, equally water-soluable but it stays more on the outer layers of the skin,’ says Mark. ‘Our lactic acid acid comes from milk and fruit sugars. Staying on the outer layers of the skin, it unglues dead cells to reveal brighter, more even skin as well as provide additional moisture to the outer skin layers.

    ‘It’s suitable for all skin types who want brighter, more even and hydrated skin. This lactic acid should be one of the FIRST exfoliating acid people go to if they are more sensitive or cautious about exfoliating.’

    Read our full guide for more information and the best product recommendations.

    Malic acid

    Malic acid is probably the least well known of the commonly used skincare ingredients. As an AHA, it also encourages skin cell turnover rate, but is found in many anti-ageing beauty products because it can encourage the production of collagen.

    Malic acid can also reduce the production of melanin, helping to prevent and improve hyperpigmentation.

    Consider your crash course in skincare acids, complete.

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