Put on a broad-spectrum sunscreen with at least SPF 15 before you go outside, even on slightly cloudy or cool days. Don’t forget to put a thick layer on all parts of the exposed skin. Get help for hard-to-reach places like your back. And remember, sunscreen works best when combined with other options to prevent UV damage.
How sunscreen works. Most sunscreen products work by absorbing, reflecting, or scattering sunlight. They contain chemicals that interact with the skin to protect it from UV rays. All products do not have the same ingredients; if your skin reacts badly to one product, try another one or call a doctor.
SPF. Sunscreens are assigned a sun protection factor (SPF) number that rates their effectiveness in blocking UV rays. Higher numbers indicate more protection. You should use a broad-spectrum sunscreen with at least SPF 15.
Reapplication. Sunscreen wears off. Put it on again if you stay out in the sun for more than two hours and after swimming, sweating, or toweling off.
Expiration date. Check the sunscreen’s expiration date. Sunscreen without an expiration date has a shelf life of no more than three years, but its shelf life is shorter if it has been exposed to high temperatures.
Cosmetics. Some makeup and lip balms contain some of the same sun-protective ingredients used in sunscreens. If they do not have at least SPF 15, be sure to use other forms of protection as well, such as sunscreen and a wide-brimmed hat.