Should I throw away the tubes of sunscreen that have been sitting in my medicine cabinet for several years? —J.A.,Torrance, Calif. 

Most likely. Sunscreens eventually start losing their sun-protecting power when the ingredients start to separate.That generally happens after the expiration date, which should be printed on the label; it’s usually two to three years after the product was made.Toss out any sunscreen that has expired or shows signs of separating, such as grittiness or changed appearance.

Find out how often people use sunscreen on themselves and their kids in our sunscreen survey. And for the most effective sunscreens, see our Ratings (subscribers only) of 10 products.