Skincare experts issue sunscreen burn warning over symbol on back of bottles

Make sure your old sunscreen bottles haven't expired before packing them for your holiday
-Credit: (Image: iStockphoto)

As peak summer holiday season approaches, Brits are heading to the shops in their millions to stock up on all the hot weather must-haves - and whether you're jetting off abroad or planning a staycation, sunscreen is always an essential.

With last 'summer' having been a bit of a wash-out, many of us will have bottles of sunscreen at the back of drawers and cupboards that were bought optimistically last year only to be barely used. However, you should think twice before you dig out those old bottles for use this summer, skincare experts warn.

While you may not think of sunscreen as something that can expire, the active ingredients can degrade over time, meaning it will be less effective at protecting you from the sun. This is a danger highlighted by the Skin Cancer Foundation, with dermatologist Rutledge Forney saying: "Sunscreen does lose its effectiveness over time, and you need to respect the expiration date. I have seen numerous sunburns on patients who realised too late that their sunscreen was expired."

If you're not sure when you bought yours, don't worry - most bottles come with a symbol indicating how long you can use them for once opened. This can vary depending on the product, and generally ranges from six months up to three years, so it's important to check each bottle you use.

Check for an illustration of a circular pot with an open lid on the back of the bottle, which should have a number followed by the letter M next to it. This is the expiry date of your sunscreen - so 6M means it will last for six months after it has been opened, 12M for 12 months, and so on.

As well as checking that your sunscreen is in date, it's also crucial to make sure you're applying it properly. According to consumer experts at Which?, many of us are making mistakes when it comes to buying and applying our sun protection - meaning that not only could you be wasting time and money, but also leaving yourself vulnerable to painful sunburn and the long-term risks associated with it, including skin cancer.

The number one error is failing to apply enough to keep you safe in the sun, with the World Health Organisation (WHO) recommending one teaspoon-sized dollop per limb or body part. It's equally important to reapply regularly, particularly after swimming and other sporting activities - however, a survey carried out in 2020 by Cancer Research UK found that little more than a third (37%) of people reapply their sun cream throughout the day.

Some sunscreens are advertised as being "once-a-day" or "water-resistant" - but Which? warns that tests have shown even these types still need to be reapplied. Tests carried out on once-a-day sunscreens indicated that their Sun Protection Factor (SPF) level fell by 74% after six to eight hours of wear, while water resistant sunscreens were made less effective by salt or chlorinated water, such as the sea or swimming pools.