Nail Polish Brands Reformulate as Chemical Restrictions on Gel Ingredients Tighten

Nail polish formulators are moving to reformulate gel products this summer as international restrictions on a common gel-curing ingredient take effect and domestic chemical rules continue to tighten. The European Union classified trimethylbenzoyl diphenylphosphine oxide, known as TPO, as a reproductive toxicant, and new UK restrictions limiting the sale of TPO-containing gel products take effect in mid-August.

TPO has been widely used as a photoinitiator, the ingredient that allows gel polish to cure and harden under UV or LED lamps, making its restriction a meaningful formulation challenge for brands that sell internationally and would rather standardize a single formula than maintain separate versions for different markets.

In the US, California's Toxic-Free Cosmetics Act has already removed formaldehyde and a list of other chemicals from cosmetics sold in the state, and a second wave of restrictions under a newer state law adds dozens more restricted substances ahead of enforcement starting in 2027, giving nail brands a domestic deadline to plan around as well.

Industry chemists say suitable TPO alternatives exist but generally cost more and can require adjusted cure times, changes salons will need to account for in appointment scheduling as reformulated gel systems roll out over the coming months.