Sunburn is a painful inflammation of the skin that is caused by overexposure to the invisible ultraviolet rays of the sun. Sunburn ranges from mild redness that disappears in a few hours to blistering, swollen, scarlet skin that peels before it heals. A severe sunburn can cause chills, dizziness, fever, and weakness. Repeated, prolonged exposure to the sun also can lead to premature aging of the skin and to skin cancer.
The seriousness of a sunburn depends on the intensity of the light and the length of time spent in the sun. The sun’s burning rays shine most intensely during the summer and from late morning to early afternoon. They travel through clouds and water, and so a person can be burned on a cloudy day or while swimming. Sand and snow reflect the rays and increase the chances of being burned on a beach or ski slope.
The skin contains a brown-black pigment called melanin, which partially provides natural protection from sunburn. Blue-eyed blonds, redheads with freckles, and other fair-skinned people have little melanin and burn easily. However, dark-skinned people rarely burn because their skin has much more melanin. Most fair-skinned people can tan without burning if they stay in the sun for only 15 minutes the first day and then increase the time by 10 to 15 minutes daily.
Sunburn can also be avoided by covering the skin or by using a lotion containing chemicals that act as a sun block or a sunscreen. A sun block filters out all the sun’s burning rays, and a sunscreen filters most of them. Commercial sunscreens are available in various strengths indicated by a number called a sun protection factor (SPF). An SPF of 2 means that, once applied, twice the normal time passes before the skin becomes sunburned. Skin experts recommend that fair-skinned people use a sunscreen with an SPF of 15 or higher. Darker-skinned people may use one with a lower SPF. Sunscreens should be applied 15 to 20 minutes before prolonged exposure to the sun and should be reapplied frequently.
The best treatment for sunburn is aspirin, which relieves the pain and reduces the inflammation. Cool baths, wet compresses, and medicated creams also provide relief.
