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Once a day sun creams

By Yvette Fletcher

An appealing product, but do they really work? Find out why Which? doesn't recommend relying on once-a-day sun creams.

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So called 'Once a day suncream' that manufacturers claim only need to be applied once a day is becoming more common. Its no surprise as carrying sun cream around, fitting it into carry-on luggage, and even just applying the stuff can be a hassle. 

Some 70% of you are either already using or interested in using these single-application sun creams. But we've found reasons why you need to be wary of these Once a day creams.  

Browse our sun cream Best Buys.

Why 'once-a-day' sun creams don't work

In 2016, we conducted our own tests on once a day sun creams using Boots Soltan Once 8hr Sun Protection SPF30 (200ml), Piz Buin 1 Day Long Lotion SPF30 (150ml), Riemann P20 Once a Day Sun Protection SPF30 Spray (200ml) and UltraSun Family SPF30 (100ml). 

First, we put them through our usual sun cream tests to check that they offer the SPF they claim – all four products passed the test.

To test whether they lasted all day, we also included a special second test. 

The once a day sun creams were applied to the backs of volunteers who then spent the day in our laboratory. 

During this time, subjects wore a t-shirt and were allowed to sit on a chair. 

After six to eight hours (this depended on how long the product claimed to last), we retested the sun cream’s SPF. 

We saw an average 74% decrease in SPF protection at the end of the tests. 

The reason for this reduction is probably the volunteer’s back rubbing against their t-shirt and the chair.

What stops your sun cream from lasting

If you sit on a sun lounger, lie on a towel or wear a t-shirt on holiday, it’s possible your once-a-day sun cream could simply be rubbed off. 

While our tests didn’t subject the sun creams to additional challenges (such as heat, sweat or water) we still saw substantial falls in the level of sun protection. 

We don’t think you should be relying on any once a day sun cream to keep you protected all day.

'Once-a-day' not allowed in Australia

Once-a-day claims aren’t permitted in Australia, where anything that leads consumers to believe sun creams don’t need to be regularly reapplied is forbidden. 

There, rules around the manufacture and labelling of sun creams are stricter than in the UK. 

When we asked Australia’s Therapeutic Goods Association why once-a-day claims aren’t permitted, a spokesperson told us the claim that a sun cream provides all-day protection is likely to be misleading, as there’s no test data available to demonstrate that the products provide the claimed level of protection throughout the day.

Which? calls for an end to the claim in the UK

We shared our concerns with Cancer Research UK (CRUK) and the British Association of Dermatologists (BAD).

Both advise against relying on any sun cream for extended periods in the sun, with the BAD saying that ‘over the course of a day, sun cream can be washed or wiped away, leaving our skin exposed. 

This is not to say that these ‘extended-wear’ sun creams shouldn’t be used at all, rather that they should be used similarly to other sun creams.’ 

Cancer Research UK recommends you reapply regularly to help get even coverage of your skin.

CRUK agrees, saying: ‘The amount of protection you get depends on how well you put it on. It’s easy to miss bits when you’re applying sun cream. CRUK recommends you reapply regularly to help get even coverage of your skin.’ 

At Which?, we don’t think ‘once-a-day,’ ‘eight-hour’ or similar single-use claims should be made on sun creams in the UK, as is the case in Australia. 

We’re not confident that one application of any sun cream will keep you adequately protected in the sun. Our concern is they may offer a false sense of security, exposing you to a greater risk of sunburn.

What is 'durable' sun cream?

In late 2018, the Cosmetic, Toiletry & Perfumery Association (CTPA) – the UK's industry body for sunscreen manufacturers – introduced a best-practice guide for claims around long-lasting sunscreens. 

It told us that the industry is now trying to move away from 'once a day' labelling, using the term 'durable sun cream' instead. 

While the best-practice guide isn't the same as there being an agreed standard, it outlines factors manufacturers should consider when developing durable sunscreens. 

It also explains that the labelling of durable sunscreens must explain the circumstances under which they should be re-applied, such as after excessive perspiring, swimming, towelling or a given period of time.

To stay safe in the sun, it's best to always apply your sunscreen carefully and regularly. And don't rely on any sun cream on its own – it should be used alongside sunglasses, clothing, a hat and the shade.

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