Sunscreens

Overview :

Many brands of sunscreens are available, containing a variety of ingredients. The active ingredients work by absorbing, reflecting, or scattering some or all of the sun's rays. Most sunscreen products contain combinations of ingredients.

The U.S. Food and Drug Administration (FDA) has required sunscreen products to carry a sun protection factor (SPF) rating on their labels since 1999. This number tells the consumer how well the sunscreen protects against burning. The higher the number, the longer a person can stay in the sun without burning.

Sunscreens are usually grouped into two major categories, namely chemical absorbers and physical blockers. Chemical absorbers absorb high-intensity UV rays while physical blockers reflect or scatter them. Chemical absorber compounds include avobenzone, padimate O, octyl methoxycinnamate, octisalate, and octocrylene. Physical blocker compounds include titanium dioxide and zinc oxide. The chief drawback of the physical blockers is their tendency to leave a white film on the skin, causing many people to use less of the product than they should for full sun protection.

A plant-derived compound that shows promise as a sunscreen is nobiletin, a flavonoid extracted from Citrus depressa or flat orange, a small citrus fruit native to Taiwan and Okinawa. Topical application of nobiletin has been shown to be effective in preventing the swelling and reddening of the skin associated with overexposure to sunlight.

Sunscreen products are sold as lotions, creams, gels, oils, sprays, sticks, and lip balms, and can be bought without a physician's prescription.