How to read a sunscreen expiration date

How to work out when to replace it

1. 1Check the container for a printed expiration date. If the date has passed, replace the sunscreen rather than continuing until the container is empty.
2. 2Check for an open jar symbol. The number beside "M" means months after opening, not a calendar month or a year.
3. 3Write down when you opened the sunscreen if it has that symbol. Add the stated number of months to your opening date to work out its replacement date.
4. 4If there is no printed expiration date, write the purchase date on the container. Sunscreen should maintain its original strength for three years; use that period to keep track of replacement.

If a numeric date could mean either day first or month first, ask the manufacturer to confirm the format. Do the same if the only marking is an unexplained code: do not assume it is an expiration date. If you cannot establish how old the sunscreen is, replacing it avoids relying on an unknown lifespan.1

What does "12M" mean?

An open jar marked "12M" means 12 months after opening. For example, opening it on 1 June gives you an opening based deadline of 1 June the following year. The symbol describes time after opening, so it is not interchangeable with a printed calendar date. Record the opening date rather than trying to reconstruct it from your last holiday.2

US sunscreens commonly carry a printed expiration date, while UK sunscreen labels can use the open jar symbol. Check the markings on your own container rather than expecting every sunscreen to use the same system.12

Does an SPF moisturizer count?

In the United States, ordinary cosmetics do not have to carry expiration dates, but sunscreen is regulated as a drug. Makeup and moisturizers with SPF are regulated as both cosmetics and drugs, so the cosmetic naming does not remove the sunscreen's stability requirements. An SPF moisturizer has two regulatory jobs, even if the front of the bottle prefers to discuss hydration.34

Keep the SPF number separate from the expiry information. SPF measures protection against UVB, the rays primarily responsible for sunburn; it is not a shelf life measurement.5

Can sunscreen go bad before the date?

Yes. Replace sunscreen before its expiration date if its color changes noticeably, it smells different or foul, it separates into layers, or it becomes dry and flaky. Direct sunlight and heat, including a hot enclosed car, can make ingredients break down faster. Keep the container out of those conditions rather than treating the printed date as permission to ignore storage.1

Expired sunscreen loses reliable protection as its active ingredients break down. It can also cause irritation or an allergic skin reaction, and bacteria or mold can grow inside the container. Do not keep using it simply because there is plenty left.1

What to check on the replacement

Choose broad spectrum protection against UVA and UVB, SPF 30 or higher, and water resistance. Check the expiry date before use. Apply sunscreen to dry skin 15 minutes before going outdoors, and reapply approximately every two hours outdoors or after swimming or sweating, following the bottle's directions. A current expiration date does not replace correct application.67