Semi-permanent nail polishes and UV gels are now everywhere. In salons, of course, but increasingly also on bedside tables at home, in kits purchased online for a few euros, in TikTok tutorials that promise perfect DIY nails for weeks. All over the world the market has exploded and it is estimated that millions of people use them regularly, driven by their durability, convenience and increasingly accessible prices.
Yet few really know what those little colorful vials contain, and what can happen to the skin when something goes wrong. An investigation conducted by the German CVUA laboratories in Karlsruhe analyzed 69 UV nail products purchased in 2025 and what was discovered is quite alarming: 55 out of 69, or 80%, did not comply with the legal requirements.
What did they find? Banned dyes, suspected carcinogens, photoinitiators toxic for reproduction and misleading labels. A panorama that is anything but reassuring, which could also closely concern Italy.
How UV nail polish works and why it can be dangerous
Semi-permanent nail polishes and gels harden through UV or LED curing. The process is based on liquid acrylates and methacrylates, reactive molecules which, activated by photoinitiators and light, form a solid plastic network.
The main risk does not only concern the hardening phase, but above all skin contact with the product that is not completely reacted or applied incorrectly. In this phase, monomers and substances not yet incorporated into the polymeric structure can come into contact with the skin and contribute to the development of contact sensitization and allergies.
Home use amplifies this risk due to the greater likelihood of imprecise application, contact with the skin and failure to respect polymerization times.
What the German laboratories found
The cosmetics team at the CVUA in Karlsruhe analyzed 59 UV nail polishes and 10 modeling gels for methacrylates, photoinitiators, stabilizers, colorants and prohibited substances. The numbers speak for themselves: only 14 products out of 69 were completely compliant. In the other 55, multiple, often overlapping violations were detected.
On the ingredient front, dyes proved to be the most widespread anomaly: 12 products contained unauthorized dyes, and in some cases there were up to three banned ones in the same bottle. In 9 products the concentrations of p-hydroxyanisole — a stabilizer subject to very stringent limits in professional preparations — exceeded the permitted threshold. In another 5, traces of phenol were found, a substance banned in cosmetics that can enter products unintentionally through plasticizers.
More worryingly, 4 products contained trimethylolpropane triacrylate, an acrylate that the EU has banned since December 2023 due to suspected carcinogenic effects on humans. Its presence suggests that some manufacturers still ignore the ban, or that certain batches were never removed from the distribution chain.
Finally, TPO, or the photoinitiator trimethylbenzoyl diphenylphosphine oxide, was detected in two products: a substance classified in 2024 as toxic for reproduction category 1B – potentially capable of compromising human fertility – and officially banned in the EU since September 2025.
In addition to problematic ingredients, the investigation highlighted serious information gaps for consumers. In 22 products at least one ingredient was missing from the INCI list: the most frequently omitted were p-hydroxyanisole (14 cases), HEMA (10 cases), TPO (5 cases). A further 11 products lacked a complete list of ingredients altogether.
Mandatory warnings were absent, incomplete, not in German or not legible in 35 out of 69 samples. In 18 products there was no indication that the product was intended exclusively for professional use, despite containing substances permitted only in that context.
Nine products were found to be false advertising: three were labeled “HEMA-free” but contained HEMA; six were presented online as suitable for home use with claims such as “suitable for beginners” or “quick and easy — whenever and wherever you want”, despite containing substances banned for non-professionals.
The alternatives that really aren’t
One of the most insidious aspects that emerged from the investigation concerns substitute substances. When an ingredient is banned or restricted, manufacturers tend to replace it with chemically similar but not yet regulated molecules.
It happened with TPO, replaced by TPO-L and BAPO, belonging to the same chemical class but currently unregulated in the EU for cosmetic use. And it happened with HEMA: many “HEMA-free” products replace it with hydroxypropyl methacrylate (HPMA), which however has a similar allergenic potential and can affect those who are already sensitized to HEMA.
As the researchers point out: unregulated does not mean safe. It simply means that that substance has not yet been evaluated by European experts. Yet companies use it, and consumers trust claims like “HEMA-free” thinking they are safe.
And in Italy?
The European Cosmetics Regulation (EC n. 1223/2009) is directly applicable in all member states, including Italy. The bans on TPO, trimethylolpropane triacrylate, limits on HEMA and mandatory warnings also apply to products sold on our shelves and in our online stores.
The Italian market for semi-permanent nail products is huge, fueled by a widespread nail art culture and a proliferation of home-use kits sold on platforms such as Amazon, TikTok Shop and Asian e-commerce sites. Many of these products come from third countries, where — as the German researchers themselves note — pre-market safety assessments rarely exist or are available upon request.
The competent Italian authorities (the Ministry of Health and the local health authorities through the NAS) carry out periodic checks, but the mass of products in circulation – especially those purchased online – makes supervision difficult. To date, there is no systematic Italian survey comparable to the German one, which does not mean that the problem does not exist: it means that we are probably not measuring it.
What to do if you use semi-permanent nail polish
Some practical indications, in light of what emerged. First of all, be wary of products without a complete label in Italian. The INCI list is mandatory: if it is missing or illegible, it is already a violation.
Then when you read “For professional use only” it is not optional. Those products contain substances that require specific skills in application. They are not meant to be used at home.
However, “HEMA-free” does not guarantee the absence of allergens. As we have seen, HPMA and other methacrylates can give the same reactions. Absolutely avoid skin contact with the product that is not yet hardened. Use gloves during application and follow the polymerization times scrupulously.
If you experience redness, itching, or blistering around your nails, see a dermatologist. Contact allergies to methacrylates can become chronic and also have repercussions in other contexts, such as dental care or the use of medicated plasters.
The final message from the German researchers is simple: until the market is regulated more effectively, and monitored more frequently, consumer caution remains the only real protection.
