Dentists have warned people not to "gamble with their oral health" with dodgy whitening products sold online. An investigation found illegal treatments were on sale that could burn through gums and destroy teeth.

Some gels sold on social media contained more than 500 times the legal limit of bleaching agent for over-the-counter products, BBC North West found. In some cases, illegal products were handed over to reporters in car parks or on sellers' doorstops.