A way of shuttling lost keratin (essentially protein) back into the hair shaft, treatments like these take porous, dull, unmanageable hair and make it shiny, healthy, strong and smooth. But while it may sound like a brilliant option for those who struggle with their lengths on a daily basis, more and more hair professionals are warning clients against back-to-back keratin treatments, as they could do more harm than good.
"Keratin has proven to be revolutionary in taking untamed hair and making it look effortlessly blow-dried," explains Vanessa Essack, stylist at Hari's Hairdressers. "The treatment wraps keratin around each hair strand, typically using heat, but as the keratin is protein-based, too much of it can make the hair brittle and snappy." Cue breakage and split ends.
Adir Abergel, hairstylist and creative director of Virtue Labs, agrees, suggesting that overdoing it on keratin will essentially 'glue down' and 'plasticise' your hair over time. "I like keratin treatments in the sense that they can often change someone's daily hair routine for the better," he told R29, "especially seeing as some people have to spend 45 minutes blow-drying their hair in the morning. That said, you can definitely over-proteinise your hair. When this happens, you'll notice that the hair becomes much harder."
Adir and Vanessa add that you don't have to get rid of the keratin aspect completely, especially if said treatments make the texture of your hair more manageable on a daily basis, but it pays to use products which will condition and maintain elasticity in the hair to tone down the effect of the hair-hardening protein. "Make sure your aftercare is not protein-based," advises Vanessa. "Most 'restructuring' or 'rebuilding' hair products include protein to strengthen, so must be avoided. Instead, use nourishing and moisturising products." Her top recommendation? Hair oil post-hair wash to keep lengths glossy. A pro go-to, Kérastase's Elixir Ultime L'Original Hair Oil, £43, nourishes, softens and maintains flexibility. Also try Hask Argan Oil From Morocco Repairing Shine Hair Oil, £3, and Dove Advanced Hair Series Shine Revived Oil Treatment, £7.75.
To make your keratin treatment last longer, Vanessa suggests investing in a sulphate-free shampoo. It's much less likely to chip away at the protein (as well as hair colour), which means your hair stays smoother for longer and visits to the salon for top-up treatments are few and far between. R29 rates Pureology Hydrate Sheer Shampoo, £19.95, YOPE Oat Milk Shampoo, £6.50, and Elvive Full Restore 5 Low Shampoo, £6.99.
If you regularly straighten or dye your hair and are reluctant to give up the strengthening products, Adir recommends Virtue's Smooth Shampoo, £14, which enlists hydrolysed keratin extracted from human hair (most others are derived from animal byproducts, according to the pro) to fill the cuticle temporarily. The star ingredient allows more moisture into the hair, increasing malleability and reducing breakage or hair hardening, typical of overdoing it on keratin blow-dries. "I wouldn’t suggest completely stopping keratin treatments at all," Adir concludes. "Just manage your haircare better in between."