Does sunscreen expire or become ineffective with age?

Sunscreens are designed to stay “fresh” for three years and the expiration date on the bottle is

reliable. It does depend on where the sunscreen has been sitting since last summer, though. If you find a bottle in car, toss it. The active ingredients in sunscreen can break down in the heat. And if your sunscreen doesn’t have an expiration date, you probably shouldn’t take the chance that it’s still good.

But what’s most important is that you are USING the sunscreen. You need about an ounce to cover your face and body and you should reapply sunscreen every two hours. If you use that formula, you shouldn’t have an old sunscreen after the summer, so you don’t have to worry about it expiring.