Some home teeth-whitening kits risk burning your gums and damaging your teeth because the kits have too much hydrogen peroxide in them.
At-home products can legally contain up to 0.1% hydrogen peroxide, while products used by professional dentists can have up to 6%.
But watchdog Which? tested 36 home kits and found that 21 of them have more than 0.1% hydrogen peroxide.
The British Dental Association’s Dr Paul Woodhouse said: ‘If you destroy gum tissue, you are never going to get it back and you lose your teeth.
‘If it penetrates the surface of your tooth, which is likely, it’s probably going to lead to the death of that tooth.’
One bleaching gel kit, from the Oral Orthodontic Materials store on AliExpress, had 300 times more hydrogen peroxide than is legally allowed in home kits – 30.7%.
This is also 5.12% more than is legally allowed in products used by professionals.
Oral Orthodontic Materials said it ‘found the mistake, corrected it in time and that the product has been removed from sale’.
Which? is concerned that the popularity of teeth-whitening kits on social media and the lack of regulation is putting people at risk of damaging their mouths.
The watchdog’s head for consumer protection policy, Sue Davies, 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.’
Dr Woodhouse said: ‘Hydrogen peroxide is a seriously strong chemical and not to be messed with.
‘Dentists are trained in its usage and they also know what whitening products are effective to use and safe for teeth and gums.
AliExpress said it has ‘promptly’ removed listings that Which? found had too much hydrogen peroxide in, adding: ‘We take product safety very seriously’.
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