Stay away from ‘once-a-day’

For the first time Which? has tested the claims of four ‘once-a-day’ sunscreens and found that they might not provide the cover they claim.


Which? tested the claims of four leading high street brands of ‘once-a-day’ sunscreen and found that after six to eight hours the average sun protection factor (SPF) decreased by 74%. This means that over the course of a day a SPF30 ‘once-a-day’ sunscreen could drop to offer as little protection as SPF8.

Which? also tested 11 widely available regular sunscreens, using strict British Standard tests, to see if they offered the SPF30 they claimed. Nearly all of the sunscreens tested passed the SPF tests. However, Hawaiian Tropic Satin Protection Ultra Radiance Lotion SPF30 (180ml) failed the SPF test twice. It was therefore branded a Which? Don’t Buy because it offered significantly less than its SPF30 claim, meaning you could be exposed to risk in the sun.


Our new research also suggests that even the cheapest sunscreens can provide good protection, such as own-brand sunscreens from Asda, Lidl and Wilko, which all offered the SPF claimed when tested. The cheapest sunscreen we tested and that passed our SPF test was Aldi’s Lacura Suncare Moisturising Sun Spray SPF30 200ml at a cost of just £2.79.

Alex Neill, Which? Director of Policy and Campaigns, said:

“Our testing shows that these sunscreens just don’t live up to their ‘once-a-day’ claims so people should reapply sunscreens regularly to ensure they have protection from the sun.


“With more than 100,000 people diagnosed with skin cancer in the UK each year, some manufacturers need to do more to ensure their sunscreens live up to the claims on the packaging.”

– ENDS –

Notes to Editors:

  • When we told Hawaiian Tropic about our results, it told us that its product has been tested at an independent, well-qualified laboratory in accordance with the international test standard. It is confident in its own test results, which it says indicated the lotion exceeds its claimed SPF, and it stands behind all of its products.

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

  • Which? shared its concerns with Cancer Research UK and the British Association of Dermatologists. Both advise against relying on any sunscreen for extended periods in the sun without regular reapplication.

  • The British Association of Dermatologists said that ‘over the course of a day sunscreen can be washed or wiped away, leaving our skin exposed. This is not to say that these ‘extended-wear’ sunscreens shouldn’t be used at all, rather that they should be used similarly to other sunscreens.’

  • Cancer Research UK said: ‘The amount of protection you get depends on how well you put it on. It’s easy to miss bits when you’re applying sunscreen. Cancer Research UK recommends you reapply regularly to help get even coverage of your skin.’

  • Which? does not think ‘once-a-day’, ‘eight-hour’ or similar single-use claims should be made on sunscreen products in the UK, as is the case in Australia.

  • Which? tested the following ‘once-a-day’ sunscreens: Soltan Once Invisible 8hr Sun Protection SPF30 (200ml), Piz Buin 1 Day Long Lotion SPF30 (150ml), Riemann P20 Once a Day Sun Protection SPF30 (200ml) and UltraSun Family SPF30 (100ml).

  • The SPF was tested using the British Standard. To test whether the four once-a-day products remain effective, we included a special second test – the sunscreens were applied to the backs of volunteers who then spent the day in the lab sitting on a chair and wearing a t-shirt. After six to eight hours (this depended on how long the product claimed to last) we re-tested the SPF of the four sunscreens.

  • Which? also tested 11 standard sunscreens including lotions, sprays and a mousse.

  • The SPF testing involves:

o   Applying a set amount of sunscreen to an area on a volunteer’s back. A UV lamp, that simulates the rays of the sun, is then directed onto the area.

o    Recordings are taken when the skin turns red, comparing the smallest dose of UV light required to turn skin red, both with and without sunscreen. Each product is tested on ten volunteers.

  • Which? also has each product tested by a panel of volunteers to determine how nice each product is to use, checking whether it makes skin greasy or sticky. For more information on buying and using sunscreens and recommended Best Buys, head to

    • Please note, copy cannot name products as having the status of a recommended ‘Best Buy’ by Which?.

  • Standard sunscreen test results:

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