How often should you apply sun cream? Plus 14 crucial questions answered by a skin cancer specialist

Telegraph

05-07-2025

There's nothing that conjures up thoughts of ' sun-drenched holidays ' quite like the slightly citrusy, sweet smell of Ambre Solaire. Even when my penny-pinching mum switched to Boots Soltan range in the 1980s, it still seemed like the essence of a Mediterranean summer, bottled. But we've learned a lot more about the dangers of tanning since then – and sadly know now that there's nothing glamorous or sexy about skin cancer.
Australia – a country where two out of three are diagnosed with the condition by the age of 70 – paved the way for making us wise up, with their 'slip slop slap' sun cream campaign over 40 years ago. And while rates of skin cancer are unsurprisingly lower here in rainy Britain, we're far from immune.
'There's a troubling rise in skin cancer cases among younger demographics,' says consultant dermatologist Dr Anjali Mahto, founder of Self London. She blames indoor tanning as well as products offering very low SPF protection. 'The latter are often marketed to appeal to Gen Z – with bright, influencer-style branding that downplays the real risks of UV exposure.'
In clinical practice, Dr Mahto sees 'a number of young patients presenting with early signs of sun damage – something that is entirely preventable with proper education and protection.'
What's more, ultraviolet radiation, both UVA and UVB, is present year-round, and its effects are cumulative and insidious – it's something to shield against every day, not just for three months a year. 'As well as melanoma, UV also contributes to fine lines, uneven skin tone and loss of elasticity,' explains aesthetics expert Dr Jo Mennie, who worked in NHS plastic surgery for 12 years.
I grilled the two doctors on the best practice for staying safe in 2025. Here are their answers.
How much sunscreen is the right amount?
If you want genuine protection don't skimp on the application. Half a teaspoon is recommended for faces and necks, and bodies need the six full teaspoons (36 grams, says Dr Mahto). 'But use your common sense, if you're larger, applying too little significantly reduces the sunscreen's efficacy.
What's the best way to apply it?
Whether you prefer an old-school cream or a spray, both get the thumbs up from the dermatologist. 'Either is effective if used correctly,' confirms Dr Mahto. 'Sprays should be applied liberally and then rubbed in to ensure even coverage. Creams provide a visual cue for coverage but require thorough application. Whatever you choose, the key is ensuring generous and even application.'
How often should you apply sun cream?
Ideally, apply sunscreen 30 minutes before sun exposure, and reapply every two hours, more frequently if you're sweating or swimming, says Dr Mennie. 'A common mistake I see is patients applying it once and assuming they're protected all day. That's unfortunately not how it works, as studies prove.' Also even if it says 'water resistant' on the bottle, swimming, sweating and towel drying can all remove sunscreen.
How can you tell which is the safest sunscreen to use?
'While SPF (Sun Protection Factor) is important, it only measures protection against UVB rays, which are responsible for sunburn. It's just one side of the sun protection equation.'
To fully protect your skin, Mahto says it's essential to use sunscreen – a term that refers to products offering broad-spectrum protection against both UVB and UVA rays. 'UVA rays penetrate deeper into the skin and are a major contributor to premature ageing and skin cancer, even when there's no visible sunburn.'
When choosing a sunscreen in the UK, look for:
SPF 30 or higher to protect against UVB
A UVA star rating of at least 4 out of 5, and
The 'UVA' logo inside a circle, which indicates the product meets EU standards for UVA protection
What SPF factor should I use? Does it depend on skin type?
Everyone should use at least SPF 30 with broad-spectrum protection, and if you have very fair skin or conditions like rosacea or melasma, make that SPF 50, says Dr Mennie. 'And even darker skin tones are still vulnerable to UVA-induced aging and pigmentation even if the burn risk is lower.'
Which is better – mineral or chemical?
Mineral sunscreens (zinc oxide, titanium dioxide) sit on the skin and reflect UV rays. 'These are brilliant for sensitive or acne-prone skin and those patients who are pregnant or breast-feeding or experiencing hormonal sensitivity in the skin,' says Mennie.
Chemical sunscreens tend to feel lighter and blend more easily, but some can irritate sensitive skin, she adds. As both have pros and cons, 'it's worth experimenting with different brands to find the one that's right for you, as the best one is the one you'll actually wear daily.'
Sunscreen makes my skin greasy or spotty – can I just wear a hat and sit in the shade instead?
'Hats and shade are helpful, but they don't block reflected UV rays completely, so sunscreen is still essential,' says Dr Mennie. She insists sunscreen won't necessarily make skin greasy, 'modern formulations are non-comedogenic and lightweight – I recommend gel-based or mineral options for oily or acne-prone skin.'
Do the 'once a day' sun creams work?
Bad news for the parents who thought these were a godsend. 'Studies have shown that 'once a day' sunscreens may not provide adequate protection for the entire day,' says Dr Mahto, who never recommends them to her patients. 'Sweating, swimming, and towel drying can diminish their effectiveness, so it's advisable to reapply sunscreen regularly, regardless of 'once a day' claims.'
Is it worth spending more on sunscreen? Are cheap brands just as good?
You don't have to spend a fortune, say the experts. 'The most important thing is that it's broad-spectrum, SPF 30 or higher, and that you apply enough – most people use half the recommended amount,' says Mennie. Some higher-end formulations offer better cosmetic finishes or added skincare benefits, she adds, 'but there are brilliant affordable options on the market.' Price does not always equate to quality in sunscreens.
What are the risks of not reapplying sunscreen?
By failing to keep topped up, sunscreen becomes less effective, or activities like swimming might remove it leaving you totally unprotected. Increasing the risk of sunburn, DNA damage, and skin cancer. Recent data confirms .
Will skipping sunscreen make me look older?
This makes premature ageing likely, says Dr Mennie. 'I've absolutely seen patients age faster from not bothering with protection. UV exposure accelerates collagen breakdown and pigmentation, so not reapplying allows UV damage to accumulate even after just a couple of hours.
'In the clinic, if I'm seeing younger patients with photodamage, fine lines, uneven tone, far earlier than I'd expect, you can be sure that they are skipping their sunscreen during overcast months or when they're 'just popping out'.'
One study found up to 80–90 per cent of visible facial aging is due to UV exposure. 'I've had patients in their 30s with premature creasing around the eyes and forehead purely from incidental sun exposure,' adds Mennie.
Is SPF in makeup or moisturisers enough?
In short, no.'The SPF in makeup or moisturiser is tested in labs at 2mg/cm² which is far more product than most of us apply. You'd need several layers to achieve the stated protection. Think of these as top-up, not your primary defence,' advises Mennie. 'I wouldn't leave the house without actual sunscreen myself, it's my number one skincare that's non-negotiable.'
Is there any such thing as a safe tan?
Unfortunately, insists Mahto, there is no such thing as a truly 'safe' tan. 'Tanning is your skin's response to injury – when exposed to UV radiation, your skin produces more melanin in an attempt to protect deeper layers from damage. So even a light tan or subtle 'glow' is a sign that DNA damage has already occurred.
'Over time, this damage accumulates, increasing the risk of premature ageing, pigmentation issues and skin cancers including melanoma. Also, it's a common misconception that a gradual tan is somehow healthier. Unfortunately, any intentional tanning, whether that's from the sun or tanning beds, comes with risks.' Don't do it.
What sunscreen do the experts personally use?
Dr Mennie: 'I wear a broad-spectrum SPF 50 every single day rain or shine, winter or summer. I use Dr David Jack's All Day Long SPF 50 as my chemical sunscreen option, and HydroPeptide's Solar Defence non-tinted SPF 50 as my mineral option depending on how my skin feels.'
Dr Mahto: 'I use a separate facial sunscreen as body sunscreens are often too heavy for my acne-prone skin, and I really like the Ultra Violette range for my face. For body, I don't spend a lot of money, I'll buy what's on offer (so long as it meets the criteria mentioned earlier). 'I don't leave the house without applying it, but if I know I'll be indoors all day (and not sitting near a window for hours) then I'll skip it – this isn't very often though!'
Dr Anjali Mahto is a consultant dermatologist of over 20 years, 12 of which were in the NHS. She's also the Founder of Self London.
Dr Jo Mennie has over 11 years of experience working as a doctor in the NHS and is a plastic surgeon with a special interest in women's health now working in the private sector.