When I first started paying attention to my skincare labels, I’d often see little logos and numbers on the side of the box and think… what on earth does that mean? And usually pretended they didn’t exist to be honest. The truth is, those tiny symbols are actually super important, especially when it comes to knowing how long your product will last and making sure it’s still safe and effective on sensitive skin. Even though you may feel like your skincare is still working the same, once it’s past its used by date the active ingredients loose their power and can end up causing unwanted irritation (which I learned the hard way). Here’s a quick guide to help you decode them.
The PAO (Period After Opening) Symbol
You’ve probably seen a little open jar symbol with a number inside it, like 6M or 12M. This is the PAO symbol, short for Period After Opening.
It tells you how long your product will stay fresh and effective after you’ve opened it.
- 6M = 6 months after opening
- 12M = 12 months after opening
For example, if your serum has “6M” on the side, you’ll want to use it within 6 months of twisting the bottle open. After this time, the formula may not perform as well and for fussy skin, expired products can sometimes cause irritation.
Sunscreen Expiry Dates
Sunscreen works a little differently. Instead of a PAO symbol, most sunscreens include an expiry date printed on the tube. Because SPF is classed as ‘medicine’, it only works properly up until the expiry date.
Even if you haven’t opened it yet, once that date passes, it’s best to let it go (I know, heartbreaking). Using expired sunscreen means you won’t get the protection promised on the label and for sensitive skin, that’s a risk not worth taking.
Hot tip: I like to keep my SPF somewhere cool and out of direct sunlight (not the car or hot bathroom shelf) to make sure it stays fresh until I’ve used it up.
Why This Matters
It might seem like a tiny detail, but paying attention to these symbols is part of taking care of your skin barrier. Using products past their PAO or expiry date can mean they don’t perform the way they should, or worse, cause irritation.
For me, learning to check these little logos has been one of the simplest ways to keep my skincare routine safe, gentle, and effective.