Sunscreens: efficacy, use, and misuse.

To provide a rational approach in the selection and use of sunscreens, we have reviewed some aspects of sun damage, the importance of genetically determined skin types, and the skin's natural protective mechanisms. In this review, we classify sunscreens, explain the sun protection factor (SPF), discuss characteristic features of specific sunscreens, supply guidelines for tanning while minimizing skin damage, and indicate which products and devices may be harmful to consumers.