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Sunscreen is a product used to protect the skin against the harmful effects of ultraviolet (UV) radiation. Exposure to the sun can lead to a number of complications including sunburn, skin cancer (melanoma and nonmelanoma), eye problems, a weakened immune system and premature aging of the skin.

There are two main types of sunscreen – chemical and physical. Chemical sunscreens absorb UV rays whereas physical sunscreens absorb, block, reflect or scatter the sun’s UV rays away from the skin. Chemical sunscreens are regulated by the U.S. Food and Drug Administration (FDA) as over-the-counter (OTC) drugs.

Because current sunscreens have the ability to absorb UV rays, as well as deflect them, the term “sunblock” is no longer used. There are also a number of sunscreen-containing cosmetics and lip balms available. Cosmetics that contain the same chemicals as sunscreens and claim to offer sun-protection are regulated by the FDA as both OTC drugs and cosmetics.  

Although some people sunburn more easily than others, everyone should use sunscreen, regardless of skin type or color. Sunscreen should be applied any day a person is going to be exposed to the sun for 10 minutes or longer, especially between the hours of 10:00 a.m. and 4:00 p.m. when the rays of the sun are the strongest.

Sunscreen should be applied year-round, not just during the summer. UV rays can damage the skin during any season or temperature. Even on cloudy or hazy days the sun can cause damage. According to the American Academy of Dermatology (AAD), 80 percent of the sun’s UV rays pass through the clouds. The rays can also reflect off of surfaces such as water, sand, snow and concrete. The AAD estimates that the sun’s reflective powers are approximately 17 percent greater on sand and 80 percent on snow.

Sunscreen alone does not provide complete protection against UV rays. It is only one component of a total program to reduce the harmful effects of sun exposure on the skin. For instance, sunscreen cannot protect the eyes from ultraviolet radiation, which can burn the cornea of the eye and increase the risk of developing a cataract. Therefore, it is important to also wear protective eyewear when outdoors.

Exposing the skin to the sun helps the body produce vitamin D. However, experts urge people to wear sunscreen and seek vitamin D through multivitamins and diet (e.g., vitamin D-fortified milk) instead.