The 'skin-ification' of hair is emerging as a powerful driver of profits as products increasingly vow to tackle breakages and fine strands - much like anti-ageing serums promise to enhance complexion.

The surge in demand for restorative haircare helped boost L'Oreal's second quarter sales by 6 per cent. 

Its boss, Nicolas Hieronimus, said customers suffering hair loss from 'fat jabs' are seeking to boost volume and promote regrowth.

L'Oreal's brands include Elvive, Garnier and Kerastase. The latter of these, sold through salons, is benefiting from what Hieronimus calls 'ongoing premiumisation' as consumers opt for more expensive solutions to bad-hair days.

This is called 'the lipstick effect', where women treat themselves to small indulgences to get through tough economic times - helped by the trend for longer locks. 

Haircare is seen as 'more of a need than a luxury', says Aela Abalos, global brand director at Tresemme, part of Unilever.

The FTSE 100 giant, which is selling off Hellmann's mayonnaise and its other food brands to focus on high-margin beauty and wellness, saw 9 per cent growth in haircare sales in the first half of the year.

There were double-digit rises in hair brands such as Dove, Sunsilk and K18, too.

K18 now offers FutureIQ Biomimetic Hair Longevity Serum, which addresses premature hair ageing. The price is £110, suggesting why the premium haircare market is forecast to expand from £95billion a year to £185billion by 2034.

But Unilever is also betting on more affordable items to pull ahead in the hair skin-ification game. Abalos says scientists at Unilever's research and development operation in Port Sunlight, Cheshire, have entirely updated the Tresemme range.

This includes Thermo Sculpt Memory, a four-step collection for the one in three women who submit their locks to straightening tongs weekly. The serum, mask, shampoo and conditioner together cost £33.50.

This is in the lipstick effect's 'sweet spot' price of £30 to £40.

While it's more than the £3.25 a big jar of Hellmann's will cost you, as the main character in hit TV comedy show Fleabag once said: 'Hair is everything.'