Which? is warning that a teeth-whitening craze driven by social media users could be leading people to buy products from online marketplaces with illegal levels of hydrogen peroxide, which can burn gums and cause permanent damage to teeth.

Its latest investigation uncovered strips, gel-filled syringes and pens with brush tips that were dangerously overloaded with one of the active ingredients used for teeth whitening – yet these products were readily available to UK consumers on online marketplaces via third-party sellers on their sites.

Worryingly 21 of the 36 teeth whiteners available on online marketplaces that were tested in the lab exceeded the legal amount of hydrogen peroxide permitted for home use.

The worst offender – teeth-whitening syringes sold on AliExpress – had more than 300 times too much hydrogen peroxide. Users of this product, costing just 85p per application, would be at particular risk of serious harm.

Teeth-whitening products sold over the counter should legally only contain up 0.1% hydrogen peroxide, while the legal limit for application by professional dentists is six per cent. However, many of the products Which? tested exceeded these levels by a significant margin.

This is particularly concerning given Which? has also seen evidence of social media users encouraging followers to apply products with high levels of hydrogen peroxide at home.

In one example, a woman told followers on TikTok she bought a bottle of three per cent hydrogen peroxide on eBay for £4 and applied it to her teeth. The video has received more than 20 million views. In this particular case the item wasn’t even marketed as a teeth-whitening product, so no laws would have been breached.

In Which?’s tests the six most dangerous whiteners had more than 100 times too much hydrogen peroxide to be legally sold.

Five of these products were purchased from AliExpress. The worst one, a ‘Teeth bleaching gel kit’ sold by Oral Orthodontic Materials store, contained 30.7% hydrogen peroxide.

Despite Crest Whitestrips not being officially sold in the UK, Which? found them being sold through a China-based Wish seller willing to ship to the UK. In lab tests, the strips were found to contain more than 132 times the legal amount of hydrogen peroxide. Procter & Gamble, owner of the Crest brand, told Which? that it doesn’t sell this product in the UK or Europe, as the law doesn’t permit its sale there.

Overall, of the eight whitening products Which? bought from AliExpress, seven had too much hydrogen peroxide to be legally sold in the UK. For Wish, four out of six breached legal limits.

Five out of nine of the products tested from eBay broke the law on hydrogen peroxide levels – the worst one contained 7.43%.

Five out of 13 of the products tested on Amazon Marketplace had illegal amounts of hydrogen peroxide – the worst offender was a pen containing 7.87% of the chemical.

Which? also tested a whitening kit available over the counter from high street retailers that contained legal and safe amounts of hydrogen peroxide. The Beverly Hills professional 2 in 1 whitening kit (£25), which is available from Lloyds Pharmacy and Superdrug, comprises a whitening pen and whitening strips.

All of the online marketplaces removed the unsafe products that went above legal limits from sale when they were flagged to them by Which?.

Which? advises consumers to seek help from a professional dentist if they are looking to get whiter teeth. Failing that, people should look to buy teeth whitening kits from a reputable high street retailer, as the legal responsibilities to ensure products are safe are stronger than on online marketplaces.

For any products that come with a gel formula, it’s worth getting a custom-made mouth tray that’s tailored to your teeth and mouth to minimise the risk of swallowing or gum damage.

Which? believes these findings raise further question marks over the checks and monitoring carried out by online marketplaces.

The consumer champion is calling for the government to give online marketplaces legal responsibility for the safety of products sold on their sites. Until then, these platforms need to enhance their checks before including sellers on their sites, and take strong action against those who break the law through selling dangerous products.

Which? has shared its findings with the Office for Product Safety and Standards (OPSS) for further investigation. Which? wants to see the OPSS urgently address these gaps in legal responsibilities as part of its review of product safety – and in the meantime, it should make sure marketplaces remove illegal products from sale as quickly as possible and ensure they do not reappear.

Sue Davies, Head of Consumer Protection Policy at Which?, said:

“It’s worrying that our tests have revealed so many of these products sold on online marketplaces – and often hyped on social media – are breaking legal limits for hydrogen peroxide and putting the health of users at risk.

“It’s clear that self-regulation is not working, leaving people exposed to a flood of unsafe products online. It is absolutely crucial that online marketplaces are given greater legal responsibility for the safety of products sold on their sites, so that shoppers are far better protected from dangerous and illegal items.”


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