Sun Protection and Sunscreens: SPF, Sunscreen Ingredients and UV rays on MedicineNet.com

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Sun Protection and Sunscreens (cont.)

What is sun protection?
How is sunburn best prevented?
What is sunscreen?
What is meant by SPF?
Are all sunscreens equally effective against UV radiation?
How do sunscreens work, and which sunscreen ingredients protect against both types of UV radiation?
How should skin sunscreens be applied?
Do water or perspiration wash off sunscreen?
Can sunscreens cause a skin reaction?
Should everyone use sunscreen protection?
Can the labels on sunscreen products be trusted in the U.S.?
Do all tanning products contain sunscreens?
What kind of sunglasses should be worn?
Is sunscreen protection necessary in the winter?
Are a good sunscreen and sunglasses enough?
Sun Protection and Sunscreens Glossary
Sun Protection and Sunscreens Index

Are all sunscreens equally effective against UV radiation?

No. Some sunscreens protect against only one type of ultraviolet radiation: ultraviolet-B (UVB). Others protect against both types of ultraviolet radiation that reach earth's atmosphere from the sun: ultraviolet-B and ultraviolet-A (UVA).

Sunscreens that protect against both UVA and UVB, and are thus classified as "broad spectrum," are recommended for everyone.

How do sunscreens work, and which sunscreen ingredients protect against both types of UV radiation?

Physical sunscreens containing zinc oxide or titanium dioxide protect against UVB and UVA. However, zinc oxide blocks more UV radiation than titanium dioxide and, therefore, is the preferred ingredient. Some chemical sunscreens can also block UVA rays. Octocrylene is a chemical known as a cinnamate that has both UVA- and UVB-absorbing properties, and the benzophenones (such as avobenzone) can also absorb both UVA and UVB rays. In July 2006, the U.S. FDA approved an over-the-counter (OTC) sunscreen preparation known as Anthelios SX that contains the UVA filter ecamsule. Ecamsule is a potent UVA-blocking compound that has been sold in sunscreen products in Canada and Europe since 1993.

How should skin sunscreens be applied?

It's a good general rule to apply a sunscreen very liberally. Anyone who skimps won't receive full protection. The sunscreen should be applied about a half hour before going outside to allow time for the sunscreen to soak in and take effect.

Do water or perspiration wash off sunscreen?

Yes. Therefore, sunscreen should be reapplied at least every two hours when staying outdoors for a prolonged period and after swimming, bathing, perspiring heavily, or drying off with a towel or handkerchief. Water- and perspiration-resistant sunscreens are available. However, even their protection will not last indefinitely.