Why your sunscreen might be giving you less protection than you think

The answers to 'how often should you apply sun cream' and 'how much sunscreen should you apply' might surprise you, as it’s more than you think. 

Whether you are in the UK or abroad, it’s important to be properly protected from the sun. This means not only wearing sun cream on exposed skin not covered by clothing, but also applying the right amount and reapplying it regularly enough. 

Dr Adam Friedmann, consultant dermatologist at Stratum Clinics, and Dr Fiona Worsnop, consultant dermatologist at The Harley Street Dermatology Clinic, shared their advice with us on sun protection and answered common questions around sun cream and how to use it properly to get the best protection for yourself and your family. 

Whilst wearing sun cream is an important step in protecting yourself and your family from the sun, it’s crucial to remember that you shouldn’t just rely on sunscreen alone for protection. Wearing suitable clothing, including a hat and sunglasses, and spending time in the shade when the sun is at its hottest is also important to avoid sun damage and getting burnt. Sunburn increases your risk of skin cancer.

How often should you apply sun cream?

Dr Adam Friedmann told us that in order to be properly protected from the sun you should apply sun cream every two hours whilst outside. 

"Reapply every two hours, and immediately after swimming, perspiring and towel drying or if it has rubbed off," said Dr Friedmann. "Up to 85 percent of a product can be removed by towel drying, so you should reapply after swimming, sweating, or any other vigorous or abrasive activity."

Explaining why it’s so important to reapply sun cream so often whilst you’re out and in the sun Dr Friedmann said, "Sunscreen becomes less effective with time. The protection fades away and by four hours it can have reduced to almost zero. So, by not reapplying sunscreen you are effectively in the sun unprotected from both the risk of skin cancer and sun damage."

"Being unprotected will also increase the likelihood of suffering with sunburn which could also lead to heatstroke as sunburn draws fluid to the skin surface and away from the rest of the body causing dehydration."

So if you don’t reapply sun cream throughout the day, then you are essentially leaving your skin exposed, and increasing your risk of sunburn and sun damage. In addition to reapplying sun cream regularly whilst in the sun, remember to check that your sun cream is still in date and hasn’t expired before you use it. It’s also important to wear protective clothing and seek shade when spending time outdoors - especially during peak sun hours - in order to prevent sunburn and protect your skin.

Cancer Research UK state, "Using sunscreen doesn’t mean you can spend longer in the sun. But it’s useful for protecting the parts of skin not covered by clothing or shade."

How much sunscreen should you apply on your face and body?

You need to apply much more sun cream than you think in order to properly protect yourself from the sun. If you don’t apply enough sun cream, then you aren’t actually getting the protection you think you are, as you need to apply enough sun cream to each body part in order to achieve the sun protection factor stated on the bottle. 

Dr Friedmann explains, "In order to achieve the sun protection factor on the label, a fingertip-sized squirt should cover an area of skin the size of a hand. So, a couple of squirts should be sufficient to adequately protect the face and about one tablespoon worth needs to be applied to each body part. This is often a lot more than people think, so it is worth measuring this for a few applications to get a feel for how much is needed."

It’s also important to remember to apply sun protection to all areas of the body that will be exposed to the sun and if it’s difficult to apply sun cream to some areas (eg the scalp if you have hair) then you should wear adequate sun protection in the form of a hat. "Any areas of the body that are exposed to the sun should be protected," advises Dr Friedmann. "Harder to reach places or awkward spots can often be missed. Places like the scalp, lips and backs of ears all get plenty of sun. The ears especially can be a prime location for skin cancer so the lobe and the folds behind the ear need to be adequately protected.

"The scalp is the highest point of the body so is likely to burn first so if you don’t wear a hat ensure you apply to your hair line and any exposed scalp. Also, large areas like the back need to be considered as parts can easily be missed when applying your own suncream.

"Don’t forget to protect your hands or feet - our hands are also sun exposed and pick up signs of ageing more quickly such as solar freckling (liver spots or age spots) - a clear indication of overexposure to the sun."

Applying more sun cream is much easier than treating sunburn and will help prevent sun damage and increasing your risk of skin cancer. So if in doubt, always apply more sunscreen than you think you need and go over any exposed areas of skin you might have missed. 

When to apply sun cream

Most sun cream products will state that you should apply sun cream to dry skin at least 20 minutes before sun exposure and reapply it regularly as required throughout the day. 

The NHS says, "If you plan to be out in the sun long enough to risk burning, sunscreen needs to be applied twice: 30 minutes before going out and just before going out."

Dr Friedmann also emphasises how important it is to wear SPF every day - especially in the summer months - to protect you from sun damage. This includes sunscreen for your face and on your body where you will have skin exposed to the sun: "SPF is the most important product in your skincare regime, and it is important to apply it every day on areas exposed to the sun from March to September. Beware of reflections too. If the sun’s rays are reflected, the radiation can increase greatly: snow up to 85 per cent increase, sand up to 17 per cent increase, water up to 5 per cent increase."

What factor sunscreen should I use?

A sunscreen with a high SPF has a better chance of protecting you from the sun than a product with a low SPF. Dr Fiona Worsnop explains, "SPF stands for sun protection factor. It refers to protection against Ultraviolet B radiation, the UV most responsible for sunburn. It is a measure of how much longer you can stay in the sun before burning, compared to wearing no SPF. The higher the SPF on the label, the better the protection it offers."

Cancer Research UK advises, "Apply sunscreen with at least SPF 30 and 4 or 5 stars. Use it generously, reapply regularly and use it together with shade and clothing." The organisation also states, "No sunscreen, no matter how high the Sun Protection Factor (SPF), can provide 100% protection from the sun. So it should be used together with shade and clothing to give your skin the best protection."

Dr Friedmann explains that while we should be looking for sun cream that is at least SPF 30, depending on your skin type you probably need an even higher factor, "I would usually recommend a factor 30 as a minimum but it does depend on skin type. At least SPF 30 for pale skin, preferably SPF 50, as we tend to apply it much more sparingly than is done during lab testing – so a SPF 30 will offer you only SPF 15 in most cases."

As well as ensuring you have a sunscreen with a high enough factor, Dr Friedmann also explains that it’s important to choose a product with a good UVA rating too: "It’s important to select a sunscreen that blocks enough UV rays to protect your skin type. It doesn’t have to be expensive but make sure you choose one that not only has a high SPF (to protect against the burning UVB rays) but one that also has at least a 4-star UVA rating, preferably 5 stars. We know that UVA can cause skin cancer and so sunscreens that protect against UVB only, are not good."

When it comes to sun protection for children, Dr Worsnop says that the best sunscreen for kids is SPF 50+ with a high star rating: "For children, you should look for a sunscreen product with a SPF 50. You should also look for an excellent protection against UVA; at least a 4 or 5 star rating is recommended. Protection against both UVA & UVB is extremely important in reducing the risk of developing skin cancer, and also reduces sun damage related skin changes which accumulate over a lifetime. It is never too early to start looking after the skin!"

Types of sun cream

There are two main types of sun cream: mineral and chemical. Dr Friedmann explains the difference, "Mineral and chemical sunblocks fundamentally work differently - chemical sunscreens are absorbed by the skin and are effective by dispersing the UV rays and mineral sunscreens lay on top of the skin’s surface and reflect the UV rays away from the body. Naturally derived ingredients used in mineral sunscreens are kinder to the skin than chemical ones - when chemical sunscreens are absorbed into the skin those with sensitive skin may find they cause irritation."

The type of sun cream you choose may depend on your skin type and what your skin can tolerate. “Anyone with sensitive skin needs to consider their sunscreen carefully – whether this is because they have irritant contact dermatitis (generally sensitive skin) or an allergic reaction to an ingredient in the sunscreen – such as a fragrance or chemical,” says Dr Friedmann. “Chemical sunscreens will on the whole be the main offenders for those with sensitive skin and should therefore be avoided - ingredients such as Oxybenzone and octinoxate. Mineral/natural/physical sunscreens (whatever you want to call them) are the sunscreens you should be using.

"So, people with rosacea or sensitive skin may benefit from mineral sunscreens containing titanium and zinc which sit on the skin, rather than chemical ones which absorb into the surface layers of the skin. However, because mineral sunscreens are not actually absorbed into the skin you will find these harder to rub in and they may leave a slight residue."

Cancer Research UK advises steering clear of aerosol sun creams, as it’s difficult to apply to correct amount of the sun cream to the skin using them, "Choose a lotion, pump spray or roll-on product, not an aerosol. Aerosol sunscreens can be patchy and do not provide a thick-enough layer for protection."

When it comes to choosing the best sun cream for you, Cancer Research UK says that it’s less about the brand name and much more important to consider the SPF factor and star rating: "It doesn’t matter which brand you buy, as long as you choose a product with at least SPF 30 and 4 or 5 stars. And remember to apply it regularly and generously! Pick a sunscreen that works for you – if you like the feel and smell, and it’s affordable, you’re more likely to use it.  Cancer Research UK does not endorse any specific brand of sunscreen."

Sun protection for babies and children

It’s important to be extra careful when it comes to babies and children and their exposure to the sun. This is because their skin is much more sensitive than adult skin, so they need extra protection to avoid sun damage to their precious skin. The NHS warns, "repeated exposure to sunlight could lead to skin cancer developing in later life. Children aged under 6 months should be kept out of direct strong sunlight." 

"Infants and children have sensitive skin which is more prone to damage from the sun than adult skin," says Dr Worsnop. "As such, it is absolutely vital to practice diligent sun protection and sun avoidance where possible. Sunscreen comes in a variety of forms such as creams or sprays. When considering which sunscreen to use on your infant or child, it is important to choose one which has both a high SPF and high UVA rating."

"Babies have extremely delicate skin which is more prone to damage from the sun than adult skin. For this reason you must take extra care to look after your little one’s skin, being careful to avoid direct sun exposure," advises Dr Worsnop. "First and foremost, keep babies out of direct sunlight where possible. If you can't find a shaded area, try to create one with a parasol buggy attachment or pram hood. Cover babies skin with light, cool clothing, so that they do not overheat but are protected. Sun-protective clothing, which actually blocks or absorbs harmful UV radiation, offers the best protection. Babies should wear a wide-brimmed floppy hat, to keep the face, ears and neck shaded, as well as sunglasses with built-in UV protection. If it is not possible to avoid direct sunlight, factor 50 sunscreen can be used minimally on babies less than six months. Baby sunscreens are mineral (physical) sunscreens, as these are less irritating to the sensitive skin of infants and children."

For children aged over six months Dr Worsnop advises, "Sun cream should be applied generously and frequently to a child over six months of age. You should apply the cream around 15 minutes before going in the sun, and re-apply every two hours, more often if your child is playing in water or perspiring. Exposure to water can alter the protection of sunscreen, even if your product is water resistant. In addition to using sunscreen, protective clothing can also be worn to add extra protection."

Find out more about sunscreen and sun safety from the NHS here.

Our experts

Dr Adam Friedmann

Dr Friedmann is a UK-trained Dermatologist who trained at King’s College School of Medicine, London. He has worked at many of London’s teaching hospitals including King’s College, St Georges, Hammersmith, Barts and the London and the Royal Free Hospitals. Dr Friedmann is Chief Medical Officer of The Dermatology Partnership and Clinical Director of the Harley Street Dermatology Clinic.

Dr Fiona Worsnop

Dr Fiona Worsnop is a consultant dermatologist at The Harley Street Dermatology Clinic. She studied Medicine at the University of Nottingham, where she also completed an intercalated Bachelor of Medical Sciences degree. She also works as a Consultant Dermatologist at King’s College Hospital in London, where she is training lead.