Why SPF Expires (and What Happens If You Use Old Sunscreen)
Degraded filters mean degraded protection.
The FDA requires that sunscreens remain stable and retain their labeled SPF for at least three years; products with no listed expiration date should be considered expired three years after purchase.
Dermatologists note that once filters degrade, an SPF 50 can quietly protect like a much lower number — and heat exposure shortens that timeline, so a tube left in a hot car may fail well before its printed date.
Questions we get a lot
Does sunscreen expire?
Yes. Filters degrade over time, so expired product gives unreliable protection. The FDA requires sunscreens to remain stable for at least three years; check the expiration date and discard any that's past date or has changed color, smell or texture — heat exposure speeds breakdown.
What happens if I use expired sunscreen?
Expired sunscreen may not protect as labeled because the UV filters have broken down, leaving you under-protected even if you apply plenty. It can also separate or change texture and is more likely to irritate skin. If a product is past date or has changed in color, smell or consistency, replace it.
How should I store sunscreen so it lasts?
Keep sunscreen out of heat and direct sun, which accelerate filter breakdown — avoid leaving it in a hot car, a sunny windowsill or on the sand all day. Store it in a cool, shaded spot, wrap it in a towel at the beach, and toss any product that's expired or visibly changed.
r/SkincareScience: 'How do I tell if my old sunscreen has gone bad?'