Get the most out of sunscreen

Easy and effective
"If used properly, sunblock is very effective at preventing the harmful effects of the sun that may lead to both skin cancer and accelerated aging," says Dr Sarah Weitzul, assistant professor of dermatology at UT Southwestern Medical Center at Dallas.

"Ultraviolet light, made up of ultraviolet A (UVA) and ultraviolet B (UVB) wavelengths, has been shown to cause mutations that lead to skin cancer in skin cells. Such mutations and other effects can be prevented by the use of sunblock," she says.

To get the most out of sunscreen, Weitzul suggests the following:

Apply liberally at least 30 minutes before exposure to the sun for full absorption into the skin. If applied too thin, the protective factor can be reduced dramatically.

Re-apply after immersion in water, sweating, contact with clothes or long periods of time (3 to 4 hours).

Use a broad-spectrum sunscreen that covers both UVA and UVB. Look for products that contain avobenzone (Parsol 1789), zinc oxide or titanium dioxide.

Use daily. Weitzul tells her patients if they are going to be out in the sun for 15 minutes or less, use a daily broad-spectrum sunscreen with a sun-protection factor (SPF) of 15. If the person will be out longer, a broad-spectrum sunscreen with an SPF of 30 is recommended.