Glycolic acid for hair? It doesn’t immediately sound like a good idea, does it? After all, the alpha-hydroxy-acid is hailed for its exfoliating abilities, and resurfacing your delicate hair strands feels more than a little counterintuitive. When it comes to our hair fibres, we want nourishment, moisture, strength – not exfoliation.
Yet here we are: glycolic acid is coming for our hair products. So far, we’re seen two major brands launch products based around the acid: Amika’s new Smooth Over treatment boasts glycolic as the leading ingredient, while L’Oreal Paris has released an entire Glycolic Gloss line.
So, what’s going on? Is this a case of murky marketing, designed to help brands dominate more shelf space in our bathrooms? Or does glycolic acid actually bring something new to the treatment table, and have a genuine reason for cropping up in our hair treatments?
Well, the honest answer is: a bit of both. As cosmetic chemist and author of forthcoming book, The Science of Beauty, Dr Michelle Wong explains, glycolic acid does have a different action on the hair to the skin. Essentially, it’s all about the bonds. ‘The proteins in your hair are full of permanent and temporary bonds that contribute to hair's strength,’ she says. ‘Hydrogen bonds are the main temporary bonds - they're broken by water, which is why wet hair is weaker than dry hair. Carboxylic acids like glycolic acid can sit inside the hair and form hydrogen bonds with the proteins, occupying spaces where water might sit, essentially preventing water from breaking hydrogen bonds.’
So actually, glycolic acid does indeed seem to be a strong ingredient for brands to use in conditioning and hair glossing treatments. However, Dr. Wong points out that this idea isn’t exactly new, adding: ‘this is also how citric acid in products like Redken's ABC range work.’ Indeed, there have long been plenty of citric acid-based products on the market, including Drybar’s Liquid Glass, Ouai's Hair Gloss and my personal favourite, Kérastase’s Premiere line.
So, it seems there isn’t anything especially revolutionary at play here – but it’s also true that these acid-based hair products are worth a try. Michael Shaun Corby, Amika’s global education ambassador, recommends a glycolic-acid hair treatment for all hair types and conditions, but especially those hoping to combat frizz. ‘These products help to give better slip when styling, reducing the drag on the hair and limiting the amount of breakage I see from my blowouts,’ he says.
Amika Smooth Over Frizz Fighting Treatment
L’Oréal Paris Elvive Glycolic Gloss 5 Minute Lamination Treatment
Indeed, I’ve tried both L’Oreal’s Glycolic Gloss and Amika’s Smooth Over, and both are brilliant. The former is a Pepto Bismol-pink cream that needs to be left to work for five minutes, and is especially effective in the glossing stakes: expect incredibly shiny hair. For frizz, I find the latter more effective, and the fact it only needs to be left on for ten seconds is a welcome bonus in early mornings. Whichever you choose, the best thing is the way hair feels post-treatment: expect the shine and smoothness you'd get from a hair mask, but without the risk of weighed-down roots or flattened volume.
Don’t discount the less hypey launches out there though: glycolic acid hair products might be today’s Tiktok bait, but citric-acid based products are every bit as effective. There’s an intensive pre-shampoo treatment in Redken’s ABC collection that is fantastic on over-straightened ends, while Kérastase’s recent Bain Décalcifiant shampoo is the best thing I’ve found for reversing the drying effects of London's hard water.
So, glycolic acid for hair? Well, yes actually: but remember, take stock of the products you already have before ordering the next big thing.
Kérastase Première Decalcifying Repairing Shampoo
Redken Acidic Bonding Concentrate
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