TPO in gel nail polish: what the EU and UK bans cover, and where US rules stand

Home gel manicure kits combine bottles of gel polish with a small lamp that cures it, and UK product safety reports show kits like these being sold through online marketplaces, including Amazon and TikTok Shop. Since September 1, 2025, one of the ingredients used to make gel harden under that lamp, trimethylbenzoyl diphenylphosphine oxide, known as TPO, has been banned from cosmetics in the European Union. Great Britain added it to its own banned list from August 15, 2026. In the US, TPO does not appear on the FDA's page of ingredients that federal regulations prohibit or restrict in cosmetics, which we checked on November 11, 2026.

What TPO does in a gel manicure

In a 2014 opinion, the EU's Scientific Committee on Consumer Safety (SCCS) described TPO as a photo-initiator: under UV light it breaks into reactive fragments that start the polymerization turning liquid gel into a hard coat, mainly in one-component UV-curable gels. The opinion gives use levels of 0.5% to 5.0% and states that the reaction uses up TPO quickly, with any small residue locked into the hardened coating.

The committee's conclusion at the time was that TPO was safe as a "nail modelling product" at no more than 5.0%, though it called the substance a moderate skin sensitizer. Until the ban, EU cosmetics law listed TPO in Annex III, the restricted list, which allowed it only for professional use in artificial nail systems at a maximum concentration of 5%.

Why the EU banned it in 2025

The ban followed from a chemical classification. EU cosmetics law prohibits substances classified as carcinogenic, mutagenic or toxic for reproduction (CMR) unless specific conditions in Article 15 of the Cosmetics Regulation are met, and the 2025 regulation records that no request for an exception had been submitted for the substances it covers. TPO was classified as a category 1B CMR substance, toxic for reproduction, under Delegated Regulation (EU) 2024/197, which applies from September 1, 2025.

Commission Regulation (EU) 2025/877 of May 12, 2025, then deleted TPO's Annex III entry and added it to Annex II, the list of prohibited substances, under its chemical and INCI names. The regulation applies from September 1, 2025, the same date as the classification. Our reading of its text is that it contains no transition period for products already in shops or salons: its only dates are its entry into force and that application date. Under the Windsor Framework, the same restrictions apply in Northern Ireland, according to the UK government's explanatory memorandum for the British rule described below.

Great Britain: banned from August 15, 2026

In Great Britain, a statutory instrument made on January 12, 2026 (SI 2026/23) added TPO as entry 1745 in Annex 2, the list of substances prohibited in cosmetic products, of the Cosmetics Regulation as it applies in Great Britain, along with other substances classified as category 1B or 2 CMR substances. That part of the instrument came into force on August 15, 2026.

The instrument allows a sell-off period. A cosmetic product containing one of those substances that was placed on the market before August 15, 2026, may continue to be made available until the end of February 14, 2027. The government's explanatory memorandum says the staggered dates give industry time to adapt, and that the instrument brings Great Britain's policy into line with Northern Ireland's.

What US rules say

The FDA says cosmetic products and ingredients, except color additives, need no approval from it before sale; manufacturers are legally responsible for safety and labeling. Its regulations single out a short list of prohibited or restricted ingredients, among them bithionol, chloroform, mercury compounds and methylene chloride. The FDA adds that it is against the law for a cosmetic to contain any ingredient that makes it harmful when used as directed or in the customary way, whether or not a regulation names that ingredient.

On why different countries prohibit different ingredients, the FDA says each regulates cosmetics under its own legal framework. It can take other countries' decisions into account, it says, but it can only act within US law, where the burden is on the agency to prove that a product or ingredient is harmful when used as intended.

The Modernization of Cosmetics Regulation Act of 2022 (MoCRA) added duties for the company named on the label, which the law calls the responsible person. According to the FDA, that company must keep records supporting adequate safety substantiation, list each marketed product and its ingredients with the FDA, and report serious adverse events linked to its products within 15 business days.

The FDA says cosmetics sold at retail, in stores or online, must list their ingredients in descending order of predominance, and that a product labeled "For professional use only" still needs that list if it is also sold at retail. The EU regulation gives TPO's INCI ingredient name as Trimethylbenzoyl Diphenylphosphine Oxide.

Kits and lamps in UK safety reports

The UK's Office for Product Safety and Standards (OPSS) publishes reports on unsafe products, and several since 2025 have involved home nail kits and lamps. None of the three below concerns TPO. They show that a kit can fail on its lamp and plug, which come under electrical safety law, as well as on what is in the bottle.

OPSS cites the Electrical Equipment (Safety) Regulations 2016 for the two plug failures and the Cosmetics Regulation for the recall. For the TikTok Shop kit, it advises owners to stop using it immediately and to ask the distributor they bought it from for redress.

What is settled, and what is not

The EU and British bans are both in force. Britain's sell-off period runs until the end of February 14, 2027; we found no transition period in the EU regulation. At the federal level in the US, as the FDA pages we read describe the rules, a gel containing TPO is covered by the general rule against harmful cosmetics and by MoCRA's duties rather than by an ingredient-specific rule. The FDA asks anyone who has had a bad reaction to a nail product to tell their doctor, then report it to the agency.