What really happens to your skin after UV exposure? Photo / 123rf
Here’s what really happens below the skin’s surface when you get sunburnt.
Wearing sunscreen should be as routine as brushing teeth or wearing a seatbelt or a bike helmet. Yet many of us – particularly those intent on getting a tan – will have felt that hot, tingling sensation on our shoulders and kicked ourselves for not protecting our skin.
Both sunburn and sun tans are physical signs that your skin is reacting to ultraviolet (UV) radiation. “They are on the same spectrum of damage with a sun tan representing the skin attempting to protect itself from UV damage and a sunburn at the extreme end where it can no longer protect itself – a sign that your skin has been severely damaged at a microscopic level,” says Dr Mary Sommerlad, a consultant dermatologist and spokesman for the British Skin Foundation.
“Repeated sunburns at any age increase your risk of skin cancer; blistering sunburns particularly before adulthood have been shown to increase the risk of malignant melanoma, the type of skin cancer that can shorten life.”
Sunburn is itchy, painful and in some cases unsightly for about a week, but the damage to the DNA in the skin cells is irreversible and can lead to cancer over time. UV rays can also cause premature ageing and pigmentation. So it’s essential that we understand the immediate and longer-term effects of sun on the skin, says Sommerlad.
After 15 minutes
You might not feel it yet but the damage has already begun. Within just 15 minutes of unprotected sun exposure, UV radiation begins penetrating the outermost layers of your skin. “UVB radiation starts damaging DNA,” Sommerlad says.
“The body’s immune system recognises this damage and triggers an inflammatory response. Blood vessels dilate, which is why in those with lightly pigmented skin, the skin can look red and feels warm and tender. This response is your body trying to bring immune cells to the area to repair the damage. In those with deeply pigmented skin, redness may be less perceptible but instead the skin may feel warm and tender.”
After two hours
The feelings of warmth, tenderness and swelling may worsen as your immune system continues to respond, Sommerlad continues. “Blistering may appear in very extreme cases – a troubling sign of dead skin cells that have lost the ability to remain cohesive.”
Pain worsens as the nerve cells are activated by the inflammation from the UV damage. Furthermore, in very severe cases there may be flu-like symptoms of chills, aching and nausea caused by a release of inflammatory chemicals into the bloodstream from the extensive UV damage.
After 48 hours
Peeling begins as your body sheds damaged skin cells trying to remove cells with irreparable DNA damage. “The skin may remain red or darker than the original skin colour. Itchy skin occurs as wound healing events start to occur in the sun burnt areas,” Sommerlad says. The process of healing the skin can release chemicals in the skin that increase the sensation of itch, she says, a bit like when you have an itchy scab.
After 72 hours
Excess uneven pigmentation appears as the initial pain and swelling subsides. This is from the overproduction of eumelanin, a type of melanin, in response to excess UV exposure, Sommerlad says. This manifests as freckles, sun spots known as solar lentigos. “These are often permanent but may fade in less sunny months only to reappear in sunnier weather. Others do not fade even in the winter months,” Sommerlad explains.
“It is important to regularly monitor your skin for any changes, particularly moles,” agrees Clare O’Connor, a suncare scientific advisor. “If you do notice anything unusual, you should visit your GP.”
After one year
Your skin remembers being sunburnt long after your tan has faded. Long-term effects include hyperpigmentation manifesting as patchy pigment, freckling and sun spots, liver spots or age spots, Sommerlad says. “Fine lines and loss of firmness can also be observed.”
These changes are broadly described as photo-damage and give the skin a prematurely aged appearance. UV eye damage can lead to early cataract formation and growths on the surface of the eye such as pterygium which can affect your vision. The World Health Organisation (WHO) estimates that up to 20% of cataracts globally are the result of UV overexposure.
After a decade
Cumulative DNA damage from repeated sunburns can eventually overwhelm your skin’s repair mechanisms, leading to mutations in genes that control the skin cells potentially leading to pre-cancer and cancerous skin changes, Sommerlad continues.
We know that melanomas arise through a complicated interplay between melanocytes – the cells that give pigment – developing uncontrolled growth and division. “It is difficult to pinpoint exactly when and why melanomas form,” she says. “We do know that some people are much more likely to get them.”
Those with lots of unusual looking moles, a history of sunburn and sun tan bed use, and who burn very easily or have a family history of skin cancer are at higher risk.
According to Sommerlad, photo-damaged skin appears saggier, more lined and wrinkled with extensive uneven pigmentation giving the skin a prematurely aged appearance.
While you can’t reverse the underlying damage from sun exposure, you can treat the skin with aftersun afterwards, which cools it and keeps it moisturised. “Lotions with aloe vera can have a cooling effect on the skin,” O’Connor explains. “It’s also important to drink plenty of water to keep yourself cool and prevent dehydration.”
Although prevention is better than cure, some skincare ingredients can help boost texture and firmness such as retinoids and peptides, adds Sommerlad, while retinoids can also help fade dark marks. “Niacinamide and antioxidants like vitamin C can help with hyperpigmentation too,” she says. “In clinic procedures such as intense pulsed light (IPL), laser resurfacing, skin peels and microneedling can also target hyperpigmentation and skin laxity but may not suit everyone and can be expensive as you might need several treatments.”
Sommerlad recommends sticking to shaded areas when spending time outside and avoiding outdoor activities when the sun is at its most potent between midday and 2pm.
“Wear breathable clothing that keeps you cool but protects from sunburns such as long sleeves and keep backs and lower limbs covered,” she advises, adding that we should all invest in a wide-brimmed sun hat and sunglasses that have UV protection.
For the parts of the body that are not easily covered such as face and neck, hands and ears, she suggests using a broad-spectrum sunscreen (SPF 30+ or 50 with a high UVA protection). “Reapply every two hours and immediately after swimming or sweating. Never rely on sunscreen alone as its application is also ‘user dependent’ and ‘reuse dependent’, and prioritise seeking shade and avoiding sunbathing as well as the protective clothing,” she says.
If you notice any signs of sunburn, you should seek shade and cover up with clothing to help stop any more damage from happening. Putting on more sunscreen doesn’t mean you can stay out in the sun for longer, Sommerlad adds.
Up to 86% of melanomas are preventable if you protect your skin in the sun, according to Melanoma Focus, with sunscreen and protective clothing. SPF stands for sun protection factor and measures the product’s protection against UVB rays; if your skin would burn in 10 minutes and SPF 30 should protect you for 30 times longer, ie about 300 minutes.
“We should use a minimum of SPF30 for all skin tones, increasing to SPF50 for those with fair or sun sensitive skin and for children,” O’Connor says. It’s important that a sunscreen also has a high UVA level. UVA rays penetrate deeper into the skin and contribute to premature ageing and skin cancer; they can even pass through a glass window or windscreen. “Always check the UVA rating when purchasing sunscreen and look for five-star rated UVA, indicating the highest level of UVA protection,” O’Connor says. “Broad spectrum” means it protects against both UVA and UVB.
Is tanning as bad as sunburn?
Yes. Tanning, even without burning, still damages DNA and increases your risk of skin cancer. There’s no such thing as a “safe tan”.
What does skin cancer look like?
Broadly speaking, Stage 1 melanoma may be a small, flat or raised mole with irregular borders and colour variation, Sommerlad says. It arises in an existing mole in about 20% of cases. Early detection and treatment may reduce the risk of it spreading beyond Stage 1.
I had sunburn as a child – is there anything I can do now?
Yes. Get familiar with “self surveillance”: checking the skin for potential skin cancers. Have a low threshold to consult a dermatologist if you notice any concerning changes to your skin; early detection of cancer is key.
Meanwhile, be meticulous with sun protection. Avoid sunbathing and suntan beds altogether even if you don’t burn. It may be worth considering a mole map if you have a lot of freckles and moles or an in-person full skin check where you can also learn how to continue checking yourself at home.
Don’t I need to go into the sun to get vitamin D?
Getting some sun on our skin can help our bodies to make the vitamin D it needs for healthy bones, according to Cancer Research UK, but whatever your skin tone, there’s no need to sunbathe or risk getting sunburn for the sake of vitamin D intake.
Can you sunburn on a cloudy day?
Yes as the clouds don’t block all UV; in fact 80% can get through. UV doesn’t heat the air – that’s infra-red light from the sun that gives the warm feeling – so you may be lulled into a false sense of security about UV strength on a cloudy summer’s day.
Can all skin types sunburn?
Yes. All skin tones, including those with deeper skin tone, can experience sunburn. While melanin offers some natural protection, it’s not complete and is actually quite variable in its level of protection. In those with olive, brown and black skin tones, sunburn may present as tenderness, swelling, or later, hyperpigmentation.