LEIGH CAMPBELL: From salicylic to glycolic, acid is skincare's new buzz word. Here's why.

Hello everyone. Today we are going to have a very basic science lesson on chemical exfoliants.

When I say basic I mean really basic, so it’s easy to understand – because it’s a damn well confusing topic. I’ll aim to keep it super simple so please, professor expert types, don’t come after me with your thousand page thesis…that’s how we all got so confused in the first place.

Shall we begin?

Take a tour in beauty editor, Leigh Campbell’s beauty bag. We’re jumping straight in.

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Unlike a scrub, which uses physical particles to sloth away dead skin cells, a chemical exfoliant has no ‘bits’ in it. Instead, it uses acid to gently eat away at the top dead layers and promote cell renewal.

Those acids are called Hydroxy Acids. There are two classes of Hydroxy Acids: you’ve got your Alpha Hydroxy Acids (AHAs) and your Beta Hydroxy Acids (BHAs). There are two classes because of how the molecules differ. Let’s look at AHAs first.

In the AHA family there’s a couple of options, made from varying ingredients and sometimes doing slightly different things:

Glycolic acid

Great for pigmentation, light scarring, fine lines and dullness, glycolic acid is probably the most popular of all the AHAs. It’s made out of plants high in sugar.

Citric acid

Made out of, you guessed it, citric fruits, citric acid is used to treat the same concerns as glycolic. It’s generally thought to be a little stronger, though that of course comes down to each product’s individual formulation.


Lactic acid

Derived mostly from milk, lactic acid is a great anti-ageing ingredient but is also good for acne. It’s generally a little more gentle than glycolic and can also help boost hydration.

Malic acid

Probably one of the lesser known AHAs, malic comes from unripe fruit and is usually used in combination with other acids, mostly to adjust a formula’s overall pH balance.

Then you’ve got your Beta Hydroxy Acid (BHA) family. When it comes to skincare there’s really only one BHA that is commonly used:

Salicylic acid

Originating from the bark of a tree, Salicylic is the go-to acid to treat acne and breakouts. It can travel a little deeper into the skin than its AHA cousins thanks to its molecule structure, and at that deeper layer can dissolve the yucky stuff causing spots and blackheads.

When looking for a chemical exfoliant you’ll often see products formulated with combinations of the above acids. Confusingly, you’ll also find these acids in many different steps along the way, like cleanser, toner, serum and moisturiser.

My general rule of thumb is to choose one hero product to do your chemical exfoliating – usually a toner or serum – and leave these ingredients out of the rest of your regime. Why? Unless you understand skincare formations, you could be overestimating the skin, causing more harm than good in the long run.

Here’s a couple of options to get you started:

Go-To Exfoliating Swipeys, $46.


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The Ordinary Glycolic Acid 7% Toning Solution, $14.50.


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Paula’s Choice 2% BHA liquid, $30.


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And that concludes today’s lesson. Everyone gets a gold star. What are your favourite acid exfoliation products? Share your picks in a comment below.