New Which? research has uncovered the hidden dangers posed by teeth whitening products sold through online marketplaces, revealing the unsafe and illegal levels of dangerous chemicals contained within them.
Teeth whiteners come in all shapes and sizes, from gel-coated whitening strips or gel-filled syringes to pens with brush tips used to paint on whitening fluid.
But more than half of the whiteners we tested contained far too much hydrogen peroxide and you could be putting your health at risk by using them.
We bought 36 teeth whiteners through online marketplaces AliExpress, Amazon, eBay and Wish. We tested them to find out how much hydrogen peroxide (the chemical used to whiten teeth) each of them contained and we also tested a widely available high street whitener for comparison.
- 21 of the 36 teeth whiteners tested from online marketplaces contained more than the legal amount of hydrogen peroxide (0.1%) permitted for home use in teeth whitening kits.
- 11 of the 36 contained more than 6% hydrogen peroxide, which is the limit in terms of what dentists are allowed to use.
- 20 products contained more than 10 times too much hydrogen peroxide.
- The six most dangerous whiteners had more than 100 times too much hydrogen peroxide to be legally sold.
The most concerning two products tested - both teeth whitening gel-filled syringes bought from sellers on AliExpress - contained around 30% hydrogen peroxide or 300 times the permissible amount for use-at-home products.
To find the best electric toothbrush for you, check out our reviews
Watch: unsafe teeth whitening kits
Our video shows what could happen if you use one of the teeth whitening products with illegal levels of hydrogen peroxide that we purchased from online marketplaces.
What our tests found
Our tests revealed huge differences in the amounts of hydrogen peroxide found in teeth whitening products bought cheaply online.
While 21 products tested contained illegal and sometimes dangerous levels of hydrogen peroxide, 12 products didn't contain any of the chemical at all. Only three had hydrogen peroxide levels within legally permitted limits.
It's these three that are likely to do a safe job of whitening teeth, but at such low levels of hydrogen peroxide, it's unclear how effective they will be.
Here's our round-up of the six worst products tested.
Teeth bleaching gel kit: 30.7% hydrogen peroxide, from Oral orthodontic materials store on AliExpress
Just 85p will buy you a syringe of teeth whitening fluid that's more likely to damage your teeth than clean them. We bought a pack of 10 through online marketplace AliExpress that when tested were found to contain more than 300 times too much hydrogen peroxide.
Sunup teeth whitening gel: 29.7% hydrogen peroxide, from Expsmile store on AliExpress
This teeth whitening gel bought for little more than £1 per syringe could seriously damage your teeth and gums. We bought it through a seller on AliExpress and found it to contain 29.7% hydrogen peroxide, or 297 times more than the legal limit.
Teeth whitening gel:14.3% hydrogen peroxide, from ZZ Shiny official store on AliExpress
This is yet another £1 teeth whitening syringe sold via AliExpress containing far too much hydrogen peroxide, in this case 14.3%, or 143 times the legal limit.
Pro teeth whitening gel: 13.9% hydrogen peroxide, from BMT store on AliExpress
Another syringe filled with far too much hydrogen peroxide and bought via AliExpress. The seller offers syringes containing 6%, 12%, 16%, 25% and 35% of the chemical, all of which are illegal for sale to consumers in the UK.
We bought the 35% product and found that they actually contained 13.9%, which is more than twice the amount a dentist could use, or 139 times more than a product sold to the public should contain.
Crest 3D Whitestrips: 13.2% hydrogen peroxide, from Yougo flagship store on Wish
With Crest Whitestrips not sold in the UK, we were curious to find them being sold through a China-based Wish seller willing to ship to the UK. In our tests, the strips were found to contain more than 132 times the legal amount of hydrogen peroxide. And we've reported on the problem of online sellers selling Crest Whitestrips to UK consumers previously.
When we spoke to Procter & Gamble, owner of the Crest brand, and it told us that it doesn't sell this product in the UK or Europe, as the law doesn't permit its sale there. But it does sell a version of the product with the permitted amounts in Europe through dentists.
Procter & Gamble told us: 'Any European site supplying Crest Whitestrips isn't supported by us and we will challenge those sites selling outside the territory they were designed for.'
Professional bleaching kit: 10.6% hydrogen peroxide, from Dear Beauty official store on AliExpress
This whitening kit is made up of three whitening pens with brush-tips. They cost around £2.30 each and we bought them from AliExpress. In our test, we found that the pens contained far too much hydrogen peroxide.
We recorded 132 times the legal amount for use-at-home products, which is again more than twice the amount that dentists are permitted to use.
Which websites sold dangerous teeth whitening products?
Teeth whiteners with illegal and dangerously high levels of hydrogen peroxide were found on sale through all four of the online marketplaces that we bought from.
All but one of the eight teeth whiteners bought through AliExpress sellers contained illegal amounts of the chemical, with 75% of the products tested from that online marketplace having too much for even dentists to use.
Teeth whiteners on test
| Number tested | Legal amounts of hydrogen peroxide | No hydrogen peroxide found | Illegal amounts of hydrogen peroxide | |
| AliExpress | 8 | 0 | 1 | 7 |
| Amazon | 13 | 0 | 8 | 5 |
| eBay | 9 | 3 | 1 | 5 |
| Wish | 6 | 0 | 2 | 4 |
| High street brands | 2 | 2 | 0 | 0 |
| Total | 38 | 5 | 12 | 21 |
Five of the nine bought from eBay sellers contained illegal levels of the chemical and five of the 13 Amazon bought products also broke the law when it comes to hydrogen peroxide and home-use teeth whiteners.
We bought six whiteners from Wish and four of them had too much peroxide for them to be legally sold in the UK. And we found products on Amazon Marketplace, eBay and Wish that contained too much of the chemical for even dentists to use.
What about the rest?
Teeth whitening products are only legal for sale over the counter if they contain a tiny amount (0.1% or less) of hydrogen peroxide.
The amounts of hydrogen peroxide found in the products we tested varied widely with more than six products containing 100 times too much to be legal, to a handful with permissible amounts and some with no hydrogen peroxide at all.
Alongside the online marketplace brands, we also tested the Beverly Hills professional 2 in 1 whitening kit (£25), which is available from LloydsPharmacy and Superdrug.
The kit comprises a whitening pen and whitening strips. We tested both pen and strips, and both contained legal and safe amounts of hydrogen peroxide.
Do some teeth whiteners not contain any hydrogen peroxide?
In our tests, 12 of the whiteners didn't contain any hydrogen peroxide, which could make them ineffective when whitening teeth, depending on what else they use to do this. But two of these peroxide-free products claimed to include the chemical in their online listings.
The listing for Whitening Gel Strips, sold by Kou Laugh store on AliExpress, notes that it contains 6% hydrogen peroxide. But we tested the strips twice and our tests found none to be present.
The Teeth Health toothpaste pen, sold by Crysle EU on Amazon, lists peroxide as an ingredient on its Amazon page, but we tested this product twice and failed to find any.
In both cases, we reported our findings to AliExpress and Amazon.
What do the experts say about the dangers of buying teeth whiteners online?
We spoke to the British Dental Association (BDA) about the dangers of online teeth whiteners.
Dr Paul Woodhouse of the BDA told us that teeth whitening products containing too much hydrogen peroxide can be dangerous: 'Using high levels of hydrogen peroxide in your mouth is like playing with fire - you risk burning your gums and permanently causing damage to your teeth.
'The pain from burns on your gums will be excruciating and high levels of the chemical could leave you with gum recession. Prolonged contact with high levels of hydrogen peroxide can also weaken the structure of your tooth, which could then need expensive root canal treatment to repair the damage.
'Be wary of over-the-counter teeth whitening products because they often fail to declare the precise chemicals used. And a study published in the British Dental Journal indicates that the chemicals used in some of these products can damage tooth enamel.'
Dr Nigel Carter, chief executive of the Oral Health Foundation told us that an increasing number of people are looking online for DIY teeth whitening products: 'This is worrying as solutions of hydrogen peroxide used are often above the 0.1% legal limit and this can lead to permanent damage to teeth and gums. That's why we only recommend visiting a qualified dentist for tooth whitening as they're professionally trained and will help you to get the results you're looking for safely.'
Which? senior scientific advisor, Kamisha Darroux, says: 'If you're in doubt about any of the chemicals used in teeth whitening products bought online, then buy from a reputable retailer, as the checks made for these products to be put on the market are much more stringent.
'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. This will prevent any of the formula from leaking out on to your gums and will minimise the risk of swallowing or gum damage. Mould-your-own trays are available online, or this can be done at a dentist.'
Safe teeth whitening advice
Don't buy teeth whiteners from online marketplaces. Our research shows that whatever online marketplace you buy from you're likely to end up with a product with a dangerously high concentration of hydrogen peroxide which could damage your teeth and gums.
With only three of the 36 teeth whiteners bought from online marketplaces - or one in 12 - containing a legal amount of hydrogen peroxide, you should steer well clear of cheap online brands.
If you're looking for teeth that are a few shades whiter, the best thing you can do is to ditch any DIY ideas and discuss this with your dentist. They will be best placed to advise on whether a treatment is suitable for you and then make a recommendation.
The NHS website explains how to find an NHS dentist and what to do if you need urgent or emergency dental care.
How we test teeth whiteners
We tested how much hydrogen peroxide each teeth whitener contained using iodometric titration. When a product was found to have too much, we retested it in the same way.
For products that contained the permitted amount (0.1% or less), we tested them once. When a product was found to have too much, we tested it twice and the percentage figures given in this article are an average of the two tests.
Which? says
Sue Davies, head of consumer protection 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 is absolutely crucial that online marketplaces are given greater legal responsibility for the safety of products sold on their sites, so that consumers are far better protected from dangerous and illegal items.'
What the online marketplaces told us
We offered each of the online marketplaces the opportunity to comment on our findings about the dangerous teeth whiteners being sold through their websites.
Amazon told us: 'Safety is a top priority at Amazon and we want customers to shop with confidence. We require all products offered in our store to comply with applicable laws and we monitor the products sold in our stores for product safety concerns. When appropriate, we remove a product from the store, reach out to sellers, manufacturers and government agencies for additional information, or take other actions.
'If customers have concerns about an item they have purchased, we encourage them to contact our customer services directly so we can investigate and take appropriate action. The products in question have been removed.'
AliExpress told us: 'We take product safety very seriously and after being notified by Which? of its findings, we took prompt action and removed the third-party product listings identified to be in violation of our listing policy.
'We are a third-party marketplace and all merchants selling on AliExpress must comply with our platform rules and policies, as well as comply with all local laws and regulations. We will take action against sellers who are found to be in violation of our terms.'
eBay told us: 'We take the safety of our users extremely seriously and work closely with authorities including Trading Standards to help ensure sellers and listings on eBay comply with laws and regulations. We have removed five of the nine listings tested by Which? and taken the appropriate action on the sellers.
'We have filters in places which automatically block listings that are unsafe or do not comply with our policies. These blocked six million unsafe listings from making it on to the site in 2020. Our teams also work around the clock as an additional safety net to manually review and remove anything that may not have been caught by our filters.'
Wish told us that its internal teams looked into the items identified and confirmed that all four listings had been taken down.
Responses from manufacturers and retailers
We also shared our findings with the sellers and manufacturers of the teeth whitening products mentioned in this article.
Oral orthodontic materials store told us that it found the mistake, corrected it in time and that the product has been removed from sale.
