Period after opening — the open-jar symbol with a number like 12M — tells the user how many months a cosmetic stays safe to use once it has been opened for the first time. It is one of the most searched symbols on any beauty label, and one of the most misunderstood, because it only tells half of the durability story. The other half belongs to a different symbol entirely.
The split is set by EU law. Under Regulation (EC) No 1223/2009, a cosmetic whose unopened shelf life is 30 months or less must carry a best-before date, marked with the hourglass symbol. A product stable for more than 30 months unopened skips the date and carries the PAO instead — the open jar with a period written inside, such as 6M, 12M, or 24M. The regulation allows the figure in months or years, but industry convention keeps it in months — 24M rather than 2Y — so the symbol reads the same everywhere. It appears on both the container and the outer box, and a handful of formats are exempt — single-use packs, sealed products that cannot be opened in normal use such as aerosols, and products with no realistic risk of deteriorating after opening.
Why It Matters to Your Brand
For any brand selling into the EU or UK, the PAO is not decoration; it is a compliance field with a paper trail behind it. The number also shapes how customers use and repurchase the product, and it varies with real risk: products used around the eyes or made for children under three typically carry shorter periods than a body lotion, because the decisive factor is microbiological — how the product resists contamination once fingers, air, and daylight reach it. In the United States, the symbol is not defined in law at all; many brands print it anyway for export alignment and shelf credibility, which is legal but should still be backed by data rather than copied from a competitor.
How the Factory Side Handles It
The PAO number is earned, not chosen. It comes out of the product's stability program — chemical and physical stability, packaging compatibility, and above all preservative efficacy testing that simulates in-use contamination. The formula, the packaging format, and even the applicator change the answer: the same cream carries different risk in an open jar than behind an airless pump. That is why an experienced OEM cosmetics partner treats the PAO as an output of testing, and why the safety assessor — not the marketing calendar — signs off the final figure. Asking for a longer period is possible; it simply buys more testing.
Frequently Asked Question
Who decides the PAO number — the brand or the factory?
Neither alone. The factory generates the evidence — stability results, challenge testing, packaging compatibility — and the qualified safety assessor signs off the period that evidence supports, inside the product's safety report. A brand can request a longer figure for commercial reasons, but the request translates into additional testing, not a bigger number on the label. Copying the 12M printed on a rival product skips the one step that makes the symbol mean anything.