The UK is not a particularly sunny country, and yet around 2,600 people die from melanoma skin cancer here every year. That is more than seven every single day, according to Cancer Research UK. And the trend is moving in the wrong direction – incidence rates are projected to rise by another 8% between now and 2040.

The tools to prevent much of this exist – they cost around £10 and sit in a glossy bottle that smells like a rather lovely pineapple and toasted coconut. And yet a YouGov survey commissioned in 2025 found that only 22% of people in the UK apply SPF at least once a day. Almost half the country is not familiar with the symptoms of skin cancer, and 40% of people who own sunscreen only buy it for holidays.

This is partly a habit problem, partly a messaging problem, and – increasingly – a misinformation problem. In 2025, false (and highly dangerous) claims that sunscreen causes skin cancer spread widely on social media, derived from an Australian independent testing found that 16 of 20 popular sunscreens didn’t meet the SPF levels on their labels. But beyond outright disinformation, there is also a vast fog of confusion about numbers, seasons, skin tones, and application frequency.

So, we deferred to the experts to demystify some of the most common myths and confusions around SPF. Here’s everything you should know about this powerful and mighty cream.

What UV radiation actually does to your skin

The sun emits two kinds of ultraviolet radiation that reach the earth’s surface, and they damage your skin in different ways. UVB rays – think B for burn – cause direct DNA damage to skin cells, triggering the mutations that can lead to cancer. UVA rays, which have a longer wavelength and penetrate deeper into the dermis, generate oxidative stress and inflammation that contributes to wrinkles, uneven skin tone, and skin cancer.

The damage from both accumulates over time, often invisibly. A tan is your skin’s panic response to injury – melanin production ramping up in an attempt to absorb further radiation. A sunburn, meanwhile, is acute DNA damage so severe that your immune system triggers cell death to prevent those cells from replicating and potentially becoming cancerous.

The evidence for sunscreen as the primary tool of prevention is, at this point, overwhelming. A randomised controlled trial in Australia found that daily sunscreen use reduced the incidence of melanoma by 50%. A Norwegian study put the reduction in melanoma risk from regular SPF 15+ use at 30%. Research consistently shows that daily SPF reduces squamous cell carcinoma risk by around 40%.

“There is no evidence that wearing sunscreen causes skin cancer. What we do know is that the sun causes most skin cancers.” – Dr Elizabeth Buzney, outpatient clinical director, Department of Dermatology, Brigham and Women’s Hospital; assistant professor of dermatology, Harvard Medical School. (Skin Cancer Foundation, 2025)

The myths that are actually costing people their lives

The trouble is not that the science is unclear. It is that a set of durable myths has taken root – some ancient, some newly turbocharged by social media – that give us plausible-sounding excuses to be lazy.

Myth 01: You only need SPF when it’s sunny

Probably the most consequential myth of the lot, because it sounds so reasonable. In fact, clouds filter some UVB rays but do not block UVA rays – the ones responsible for deeper skin damage and melanoma risk. Up to 80% of UV radiation reaches your skin on a fully overcast day.

Winter is not safe either: snow reflects UV rays, effectively doubling your exposure during outdoor activities. Dr Derrick Phillips, consultant dermatologist and British Skin Foundation spokesperson, explains:

“Yes there is less intensity, but it can still accumulate damage that can lead to skin cancer, aging and other untoward effects. You’d think that sunscreen isn’t that important but [exposure to UV] is a cumulative effect.”

Myth 02: A higher SPF means you can apply it once and forget it

No sunscreen, at any SPF, lasts all day. Both SPF 30 and SPF 50 need reapplying every two hours when outdoors, and immediately after swimming or sweating. The number indicates the degree of UVB filtration, not the duration of protection. Treating a high SPF as a one-and-done application is one of the most common and least talked-about errors in sun care – and it may actually encourage riskier behaviour, with people spending longer in the sun under a false sense of security.

Myth 03: SPF 50 is dramatically more protective than SPF 30

The gap is smaller than the numbers suggest. SPF 30 blocks approximately 97% of UVB rays; SPF 50 blocks around 98%. That one-percent difference can matter over long days in intense sun – particularly for people with a history of skin cancer or very fair skin – but for daily use, a well-applied SPF 30 is highly effective. The more critical variable is not the number; it is the quantity applied and the consistency of reapplication. Most people apply far less than the amount used in laboratory testing, meaning their real-world protection is considerably lower than the label states. A generous, even application of SPF 30 will outperform a stingy, patchy application of SPF 50 every time.

Myth 04: People with darker skin tones don’t need SPF

Melanin does offer some natural protection against UV radiation, but it is not a substitute for sunscreen. Dr Brendan Camp, a New York dermatologist, is clear: even deeply pigmented skin is susceptible to sunburn, sun damage and skin cancer. There is an additional and serious concern: sun damage can be harder to detect on darker skin tones, meaning diagnosis may be delayed. The same dermatological guidelines apply regardless of skin tone.

One practical distinction worth noting: formulation matters. Sheer mineral sunscreens have come a long way, and there are now plenty that absorb without the chalky white cast that put so many people off mineral SPF in the first place.

Myth 05: Wearing SPF will give you a vitamin D deficiency

The concern is understandable – UVB rays trigger vitamin D production in the skin, and sunscreen filters UVB. But the evidence does not bear it out. A 2019 study published in the British Journal of Dermatology recorded increased vitamin D levels in participants during a week of high-UV weather, even when sunscreens were applied correctly and sunburn was prevented.

The 2025 Sun-D Trial, a randomised controlled study, found daily sunscreen application did not meaningfully reduce vitamin D levels. Most people do not achieve laboratory-level coverage, some skin is always exposed, and even filtered sun still permits some vitamin D production. Dietary sources and supplementation cover the rest.

Myth 06: You don’t need SPF indoors

UVA rays – the ones that age skin and contribute to melanoma – penetrate glass. Dr Camp notes that windows allow the passage of UVA rays, which damage collagen and elastin and can contribute to sunburn formation. If you work near windows, drive regularly, or spend time in sun-facing rooms, your skin is accumulating UVA exposure even on days you never step outside. The damage is ambient, invisible, and decades in the making before it presents as premature ageing, hyperpigmentation, or something more serious.

How to actually read the numbers

The SPF labelling system measures UVB protection only. It tells you nothing about UVA coverage – which is why “broad-spectrum” is the most important phrase on any sunscreen label. In the UK and EU, look for the UVA logo (a circle containing “UVA”), which indicates UVA protection meets the EU minimum standard of at least one third of the stated SPF value.

• SPF 15: blocks 93% of UVB. The bare minimum for daily use; fine for people who spend almost no time outdoors.
• SPF 30: blocks 97% of UVB. The dermatological baseline recommendation for most people, most climates, year-round – including the UK.
• SPF 50: blocks 98% of UVB. Worth it for extended outdoor exposure, high altitude, very fair or sensitive skin, or a personal history of skin cancer.
• SPF 50+: the ceiling of meaningful protection. Beyond this, gains are negligible. The number offers marketing value more than additional defence. Apply correctly; effort matters far more than SPF rating.

“It’s a misconception that you have to go with a super high SPF to get a benefit. If a lower SPF is what you’re happy wearing, then that is better than not wearing sunscreen.” — Stanford Medicine dermatology experts, 2025

What a good SPF habit actually looks like

The baseline is simple: a broad-spectrum SPF 30 or higher applied every morning to all exposed skin. For the face and neck, that’s around half a teaspoon, and on days when you’re spending meaningful time outdoors, it should be reapplied every couple of hours.

Where we tend to fall short is rarely the obvious areas. It’s the small, easily missed ones that make the difference over time: ears, the hairline, the back of the neck, hands, lips (an SPF lip balm really does matter), and the scalp for anyone with thinning hair or a defined parting.

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