Sun knows no season.

• Position: Skin Cancer

The sun knows no season. It is just as bad for your lips and skin in cold as in warm temperatures. The problem is that, regardless of the weather, most people do not think about protecting their lips by wearing a lip balm with SPF (sun protection factor).

"Lips are more susceptible to sunburn than other parts of the body because [they] lack melanin, a dark pigment contained in other types of skin, which acts as a natural sunscreen," says Charles Zugerman, associate professor of clinical dermatology at Northwestern University Medical School in Chicago.

Lips also are more vulnerable because they are more frequently wet--via licking and consumption of food and drink--which can intensify the burning effects of the sun.

In addition to discomfort and unattractive drying and peeling of the lips, sun exposure can trigger cold sores or fever blisters. Moreover, chronic sun exposure can lead to potentially serious cancers, including squamous and basal cell carcinoma, conditions that produce nodules or red, scaly patches and result in significant, permanent scarring.

If that were not enough, "Prolonged or excessive sun exposure ... can suppress the immune system, and that weakens a vital defense against the development and spread of various types of skin cancer," cautions Zugerman.

Other than avoiding sunlight entirely all year round, which is neither practical nor desirable, lip balms with sunscreen offer the best possible lip protection, but not all lip balms with sunscreen--nor even all sunscreens--are the same. Most traditional lip balms primarily protect against UVB rays--the ones most responsible for sunburn, and which can be blocked by window...