How long does unopened sunscreen last?
A sealed bottle is not exempt from its expiration date. In the US, sunscreen can be sold without a printed date only when stability testing shows it remains stable for at least three years. For an undated bottle, count three years from purchase, not from the day you finally open it.1
If you cannot establish how old the sunscreen is, throw it away. Write the purchase date on an undated bottle, so the cupboard does not become an archive of unsolved sunscreen cases. Keep track of printed expiration dates too, so you can replace bottles before you need them.12
Can I use sunscreen from last summer?
Yes, if it is still within its expiration date, has been stored away from excessive heat and direct sunlight, and has no signs of spoilage. For undated US sunscreen, it must have been purchased within the last three years. Last summer's purchase is not automatically this summer's rubbish; check the bottle rather than replacing it just because the season changed.12
Sunscreen can spoil before its expiration date. Replace it if you notice an obvious colour change, a different or foul smell, separated layers, or a dry and flaky texture. A normal appearance does not override an expired date: discard expired sunscreen even if you see none of these changes.12
Heat can make sunscreen ingredients break down faster, including when a bottle is left in direct sunlight or a hot car. Protect unopened bottles as well as bottles you are using. Outdoors, keep the container in the shade or wrap it in a towel rather than leaving it exposed to the sun.12
How do I read sunscreen expiration dates?
A printed expiration date tells you when to discard the sunscreen. An open jar symbol with a number and the letter M tells you how many months the product lasts after opening. The open jar symbol describes use after opening, which is a lot of administrative work for a tiny drawing.3
The three year purchase rule applies to undated US sunscreen; products bought elsewhere can have different labelling, including the open jar symbol used on UK products. Do not read that symbol as permission to keep an unopened bottle indefinitely.13
What should I use instead of expired sunscreen?
Choose an unexpired, broad spectrum sunscreen with SPF 30 or higher and water resistance. Apply it to dry, exposed skin 15 minutes before going outdoors. Most adults need about one ounce to cover skin not covered by clothing. Reapply approximately every two hours outdoors and after swimming or sweating, following the bottle's directions.4
