UK Cosmetic Regulation Changes 2026 (SI 2026/23)

Great Britain made significant changes to its cosmetic rules in 2026 through SI 2026/23. If you sell cosmetics in England, Scotland or Wales, this instrument bans a UV filter, prohibits a set of CMR substances, restricts a fragrance ingredient and changes a labelling threshold each on its own deadline. This guide explains what changed and the dates you need to know.

For the parallel EU changes and the bigger picture, see our pillar guide to cosmetic regulation changes in 2026.

What is SI 2026/23?

SI 2026/23 The Cosmetic Products (Restriction of Chemical Substances) Regulations 2026 is a statutory instrument adopted in January 2026 that amends the UK Cosmetics Regulation as it applies in Great Britain. It is part of the UK's post-Brexit, safety first approach, in which Great Britain runs its own scientific reviews and issues its own legislation rather than automatically following the EU.

Importantly, it applies to Great Britain England, Scotland and Wales. Northern Ireland continues to follow EU cosmetic rules under the Windsor Framework, so for NI the relevant changes are the EU ones, not SI 2026/23.

The 4-MBC (Enzacamene) ban

SI 2026/23 bans the UV filter 4-MBC, also known as Enzacamene or 3-(4-methylbenzylidene) camphor, removing it from the list of permitted UV filters and adding it to the prohibited list, due to concerns about endocrine and reproductive effects. Sun-protection and other products that used this filter must be reformulated.

The deadlines for 4-MBC are a placing-on-market cut-off of 15 July 2026 and a longer sell-through (off-shelf) deadline of 15 January 2027 for compliant existing stock. So new products with 4-MBC could not be placed on the GB market after mid-July 2026, while stock already on the market had a few more months to clear. If you make sun care, this is a priority see our UV filters guide.

The CMR substance bans (including TPO)

SI 2026/23 also adds a set of around sixteen newly classified CMR substances to the GB prohibited list. The one most likely to affect everyday products is TPO (a photoinitiator used in UV-cured gel nail products), which is now banned in Great Britain. Most of the other substances are industrial or intermediate chemicals not commonly used in cosmetics, but every formula should still be checked.

The CMR deadlines are slightly later than the 4-MBC ones: a placing-on-market cut-off of 15 August 2026 and a sell-through deadline of 15 February 2027. We look at the TPO ban specifically including what it means for nail technicians in our TPO guide.

The formaldehyde labelling change

A change that is easy to overlook concerns formaldehyde-releasing preservatives. SI 2026/23 lowers the threshold at which a product must carry the “releases formaldehyde” warning from the previous higher level down to a finished-product formaldehyde concentration of 0.001%. This means some products that previously did not need the warning now do, even though their formulation has not changed.

Because this is a labelling change, it requires checking which of your products contain formaldehyde-releasing preservatives, recalculating the released formaldehyde, and updating labels where the new threshold is crossed. The relevant deadline aligns with the mid-July 2026 date. Our label warnings guide covers mandatory warnings generally.

Hexyl salicylate restriction

SI 2026/23 also addresses hexyl salicylate, a fragrance ingredient newly classified as a CMR, by adding it to the restricted list with safe-use conditions rather than banning it outright. This mirrors the EU's treatment of the same substance, though as ever the exact conditions and dates should be checked against the GB text rather than assumed identical to the EU's.

If your products are fragranced, hexyl salicylate is worth checking alongside the wider fragrance-allergen labelling changes. Fragrance is one of the areas where UK and EU rules are both evolving, so it repays careful attention for multi-market sellers.

Key GB deadlines at a glance

Pulling the dates together: the 4-MBC ban and formaldehyde labelling change take effect for placing on the market from 15 July 2026, with sell-through to 15 January 2027. The CMR bans (including TPO) apply from 15 August 2026, with sell-through to 15 February 2027. These staggered dates contrast with the EU's single, no-transition 1 May 2026 cut-off, underlining how the two markets now diverge.

Because the dates differ by substance, the practical approach is a per-product transition calendar: list which affected substances each product contains, note the relevant placement and sell-through dates, and plan reformulation, relabelling and stock management around them.

What GB–EU divergence means in practice

SI 2026/23 is a clear illustration of a trend that is only going to grow: Great Britain and the EU increasingly run on separate tracks. The same TPO ban applies a year apart in the two markets; the EU's Omnibus VIII gives no sell-through while the UK staggers its dates into 2027; and each side restricts hexyl salicylate on its own terms. For a brand selling only in Great Britain, you simply follow the GB rules. For a brand selling in both, you cannot assume one set of compliance work covers the other.

In day-to-day terms, this means maintaining two compliance pictures: GB products checked against the UK annexes and SI 2026/23 dates, and EU products checked against the EU annexes and Omnibus VIII. Your labelling can differ too the GB formaldehyde threshold change, for instance, is a UK measure. The same physical product may need different documentation, and sometimes different labels, for each market.

This is precisely why the Responsible Person role is per-market, and why brands expanding across the UK and EU benefit from someone tracking both rulebooks. The cost of duplicated checking is real, but far smaller than the cost of assuming alignment and discovering, too late, that a product compliant in one market was never compliant in the other.

UK 2026 changes checklist

• Check sun care for 4-MBC (banned; placement 15 Jul 2026).

• Check gel nail products for TPO (banned; placement 15 Aug 2026).

• Recalculate and relabel for the lower formaldehyde threshold (0.001%).

• Review fragranced products for hexyl salicylate conditions.

• Build a per-product transition calendar of GB deadlines.

• Update CPSR, PIF, labels and SCPN notification after changes.

Frequently asked questions

What is SI 2026/23?

The Cosmetic Products (Restriction of Chemical Substances) Regulations 2026, a UK statutory instrument adopted in January 2026 that amends the GB Cosmetics Regulation banning 4-MBC, prohibiting CMR substances, restricting hexyl salicylate and changing formaldehyde labelling.

When do the UK 2026 changes take effect?

The 4-MBC ban and formaldehyde labelling change apply from 15 July 2026 (sell-through to 15 January 2027); the CMR bans apply from 15 August 2026 (sell-through to 15 February 2027).

Is TPO banned in the UK?

Yes. TPO, used in UV-cured gel nail products, is among the CMR substances banned in Great Britain under SI 2026/23, with placement prohibited from 15 August 2026.

What changed about formaldehyde labelling?

The threshold for the mandatory 'releases formaldehyde' warning was lowered to a finished-product concentration of 0.001%, so some products now need the warning even without a formulation change.

Does SI 2026/23 apply in Northern Ireland?

No. Northern Ireland follows EU rules under the Windsor Framework, so the EU changes apply there. SI 2026/23 applies to Great Britain England, Scotland and Wales.

Do I need to relabel products even if the formula is unchanged?

Possibly. The lower formaldehyde-releaser threshold means some products now need the 'releases formaldehyde' warning despite no formulation change, so you should recalculate released formaldehyde and update labels where the 0.001% threshold is crossed.

How is the UK approach different from the EU's in 2026?

The UK uses phased placement and sell-through deadlines (mid-2026 into early 2027), while the EU's Omnibus VIII applied from 1 May 2026 with no sell-through. The substances and conditions also differ in detail, so the two must be checked separately.

References: The Cosmetic Products (Restriction of Chemical Substances) Regulations 2026 (SI 2026/23, legislation.gov.uk); UK Cosmetics Regulation as retained; OPSS and SAG-CS guidance; GB CLP Regulation. General information only, not legal advice; verify current requirements for your products.