Yes, sunscreen expires. The active ingredients break down over time, and a bottle that's been sitting in a hot car may fail well before the date on the label. Using old sunscreen is worse than using none at all—you think you're covered when you're not.

How long it lasts

In the U.S., the FDA requires sunscreens to stay at full strength for at least three years from manufacture. Most bottles now print an expiration date—treat that as the cutoff. No date? Write the purchase date on the bottle and toss it after three years.

If you apply the recommended amount (about one ounce, or a shot glass, for your whole body), you'll finish a bottle in a few weeks anyway. Expiration mostly matters for half-used tubes left over from last summer.

When to throw it out

Past the expiration date—always. Separated, grainy, or an off smell—always. When in doubt, replace it. An expired SPF 50 might behave like SPF 15 or offer almost nothing.

Heat kills sunscreen faster than age. A tube left in a car trunk or beach bag can go bad in weeks, even if the label says it's good for three years.

Chemical vs. mineral

Chemical filters like avobenzone break down faster, especially with heat and light. Mineral sunscreens (zinc oxide, titanium dioxide) tend to hold up longer in storage—but both types expire, and neither is worth keeping past its date.

How to store it

Keep sunscreen at room temperature (59–86°F / 15–30°C), out of direct sun. A cool closet beats a steamy bathroom or a car glove box. At the end of summer, move it somewhere dark and check the cap is sealed before next season.

Check the date before every beach trip, store bottles out of heat, and buy a fresh one if anything looks or smells off. A $12 replacement beats a sunburn you didn't see coming.