Sunburn is caused by excessive exposure to the sun or other UV radiation and can take place within minutes. Sunburn occurs because the skin is unable to make melanin fast enough to protect itself. Blood flow to the damaged area increases, and the sunburn may not be felt until up to four hours later. Pain will peak between 8 and 24 hours after the sunburn has occurred and can last for up to 48 hours.
The damage from a continuous sunburn or extreme sunburn increases the chances of skin cancer dramatically. If severe blistering due to sunburn occurs during childhood, the chances of having skin cancer later in life are doubled.
Sunburn results in permanent skin damage to the cells, leading to skin cancer.