When you buy beauty products, you often see symbols and dates on the packaging without always knowing what they mean. Two of the most important are the PAO (Period After Opening) and the expiration date. Although they seem similar, they have very different functions.
What is PAO?
The PAO (Period After Opening) indicates how long you can use a product once it is opened, while maintaining its safety and effectiveness.
It is represented by an open jar symbol with a number followed by the letter "M" (months). For example:
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6M = to be used within 6 months after opening
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12M = to be used within 12 months
This symbol is very common on creams, makeup, and sunscreens.
Why is PAO important?
Once opened, the product:
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is exposed to air
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can be contaminated by bacteria
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sees its active ingredients degrade
Even if the product still seems "normal," it may no longer be safe or effective.
What is the expiration date?
The expiration date (or best-before date) indicates how long an unopened product retains its quality under good conditions.
It usually appears as a specific date or with an hourglass symbol.
When is it used?
The expiration date is particularly indicated when:
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the shelf life is less than 30 months
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the formula contains sensitive ingredients
Key differences between PAO and expiration date
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PAO: starts counting after opening
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Expiration date: concerns the unopened product
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PAO: usage period after opening
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Expiration date: shelf life before opening
Which one should you follow?
The answer is simple: both.
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If the product is unopened → check the expiration date
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If the product is opened → observe the PAO
👉 Example:
You buy a cream that expires in May 2027 with a PAO of 12M.
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If you open it in July 2026 → you could theoretically use it until July 2027
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But if the expiration date is May 2027 → that's the date you must respect
👉 Always follow the earliest date.
Practical advice
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Note the opening date on the product
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Avoid using a product whose smell, texture, or color has changed
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Do not share your cosmetics, especially makeup
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Store them in a cool, dry place