Skip to Content

SHARE

Sun Protection Factor (SPF)

Sun protection factor (SPF) is a number on sunscreen labels that shows how long skin can be in the sun and maintain a low risk for sunburn. The higher the SPF number, the longer it protects a person from the sun's burning rays.

It is important to read the information on the sunscreen label about the SPF factor listed on the label and how much protection it gives the skin. The sunscreen should be applied according to the directions on the label so it is most effective in protecting the skin from the sun's ultraviolet rays.

No sunscreen gives total protection, but "broad-spectrum" sunscreens that contain ingredients such as avobenzone, benzophenones, cinnamates, salicylates, sulisobenzone, titanium dioxide, and zinc oxide usually protect from ultraviolet A and B (UVA and UVB) rays. The label of the sunscreen product will say what types of UV rays it protects the skin from.

Sweating heavily, swimming, or doing other water activities reduces the SPF because sweat or water on the skin will reduce the amount of protection the sunscreen provides. Sunscreen needs to be reapplied more frequently during these activities.

Decision Points

Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.

You'll find Decision Points to help you answer questions about:

Interactive Tools

Get started learning more about your health!

Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.

Symptom Checker

Feeling under the weather?

Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.