Sunburn

What is sunburn?

If your skin has gone red in the sun, it’s sunburnt. Sunburn doesn't have to be red-raw, peeling or blistering.

A sunburn is a clear sign that ultraviolet (UV) radiation from the sun has damaged the genetic material in your skin cells - their DNA.

Damaged DNA can cause cells to start growing out of control. This can lead to skin cancer. Getting a painful sunburn just once every two years can triple the risk of melanoma, the most serious type of skin cancer.

Your body's attempt to repair this damage is what causes the painful symptoms of a sunburn.

Check out our sunburn animation below for an illustration of what happens to your skin when you get sunburnt.

Why are sunburns red, hot or painful?

When UV radiation damages DNA, your body tries to repair the damage. The blood vessels in the local area swell, allowing blood to rush into it. This is why sunburn looks red.

Blood inside your body is also hot, which is why it feels like sunburns give off heat - actually, they are usually no hotter than your core body temperature.

The wider blood vessels allow the cells of your immune system to travel to the site of the damage. They also release chemicals which trigger inflammation - this is why bad sunburns are swollen and painful.

Why do sunburns peel?

Sometimes, the sun damages skin cells so severely that they must be destroyed. Peeling after sunburn is your body's way of getting rid of these damaged cells. This is necessary because cells damaged by the sun are at risk of becoming cancerous.

Although skin peels and new skin layers form, some sunburn damage may remain. This can increase your risk of skin cancer. So it is important to try to avoid burning in the first place.

Are sunburns like burns you get from touching something hot?

No, sunburns are caused by ultraviolet radiation (UV) from the sun, which does not feel warm. The heat in the sun comes from infrared rays, which do not burn your skin. This is why people can still burn on cool days.

When you touch a hot object, your skin may also become red, swollen and painful. But the DNA inside your skin cells is not damaged. Both heat burns and sunburns will fade, but only sunburns can cause lasting damage to the DNA in your skin cells. Check out our sunburn animation for more information on this.

How does the sun damage DNA?

There are two major types of UV rays that damage our skin

• UVB is responsible for the majority of sunburns and it can cause skin cancer.
• UVA penetrates deeper into the skin. It ages the skin, but contributes much less towards sunburn.

Recent evidence tells us that both UVA and UVB can damage DNA in the skin, which can lead to skin cancer. A third type of UV ray, UVC, is the most dangerous of all, but it is completely blocked out by the ozone layer and doesn’t reach the earth's surface.

Is the DNA damage from the sun permanent?

Your body has ways of repairing most of the damage. But it is not perfect - some damaged DNA can be left behind. This is why it is important to avoid getting caught out by sunburn.

Do I have to worry about sunburn in the UK?

Most people think about sunburn as something that happens on holiday or in hot, sunny places. But sunburn can happen just as easily at home as on holiday.

Many cases happen when people are not deliberately 'sunbathing'. You may be outdoors watching sport, doing the gardening or just sitting in the park.

How can I protect myself?

Don't let sunburn catch you out. Whether at home or abroad, use shade, clothing and SPF15+ sunscreen to protect your skin.