Shelf Life and Period After Opening (PAO)
What the little open-jar symbol with a number means, the difference between shelf life and period after opening, and why the US does not require either but you should still set them.
Two different clocks run on a cosmetic. Shelf life is how long the product stays good sitting unopened on a shelf, and period after opening, or PAO, is how long it stays safe and effective once a customer breaks the seal. The PAO is what the little open-jar symbol with a number means: “12M” tells the customer to use the product within 12 months of opening it.
What the symbols mean
The open-jar symbol with a number and an M is the PAO. Common values track how stable a product is once air and fingers get to it: mascara and liquid eye products often run 3 to 6 months, most skincare 6 to 12 months, and stabler products longer. A separate symbol, an hourglass, is used in some markets for a fixed expiration date on products that do not last long unopened.
The US and EU rules are different
The US and the EU treat this very differently, and it matters if you sell in both.
In the US, none of it is required. The FDA does not require expiration dates or a PAO on cosmetics. Instead, the manufacturer is legally responsible for making sure a product is safe for its expected life. Many US brands add a PAO anyway, because retailers and customers expect it and because it is needed to sell abroad.
In the EU, it depends on shelf life. Products with a shelf life over 30 months must show a PAO with the open-jar symbol. Products that last 30 months or less must instead show a “best used before” date. Products that do not deteriorate after opening, like single-use packets, aerosols, and some powders, are exempt.
How to actually set and label a PAO
You do not guess these numbers, you test for them, and the process is the same whether you formulate yourself or use a contract manufacturer, who can usually run or arrange the testing for you. Here is what that looks like in practice.
Run stability testing. A cosmetic testing lab holds your product at normal and elevated temperatures over weeks or months and checks whether the formula, color, scent, texture, and packaging hold up. This is what sets your unopened shelf life. Labs like Intertek and Eurofins offer it, and many contract manufacturers arrange it for you.
Run a challenge test. Also called preservative efficacy testing, this deliberately contaminates the product with microorganisms and measures how well the preservative system controls them once the package is opened. That result is what your PAO is really based on. Ask the lab for ISO 11930 or USP <51>, the two standard methods. Water-based products need this, and truly anhydrous products like oils and balms often do not.
Set the numbers from the results. The stability report gives you the unopened shelf life, and the challenge and stability data together give you a PAO you can defend, commonly 6M, 12M, or 24M, with shorter 3M to 6M windows for mascara and other eye products.
Put it on the package. Print the open-jar PAO symbol with your number (for example “12M”), and add a batch code so every unit traces back to its production run, which you will need if you ever have to recall.
Even though US law requires none of this, do it anyway. Retailers like Sephora and Ulta ask for stability and safety data before they will stock you, the EU and other markets require it, and it backs up the safety substantiation that MoCRA now legally requires. A tested PAO is one you can stand behind. A guessed one is a liability.
Frequently Asked Questions
What does the 12M symbol on cosmetics mean?
The open-jar symbol with “12M” is the period after opening. It means the product is meant to be used within 12 months of the first time it is opened. Other common values are 6M and 24M, and shorter periods like 3M or 6M are typical for mascara and other eye products.
Does the FDA require expiration dates on cosmetics?
No. In the US, the FDA does not require expiration dates or a period-after-opening symbol on cosmetics. The manufacturer is responsible for ensuring a product stays safe for its expected shelf life. Many US brands still add a PAO because retailers and customers expect it and because other countries require it.
What is the difference between shelf life and PAO?
Shelf life is how long a product stays good unopened. Period after opening is how long it stays safe and effective after the seal is broken, shown by the open-jar symbol. A product can have a long shelf life closed but a much shorter safe window once it has been opened and exposed to air and skin.
Sources
- FDA, “Shelf Life and Expiration Dating of Cosmetics”. The US position that expiration dating is not required and rests on the manufacturer.
- Marie Gale, “Using the Open Jar and Hourglass Symbols”. The EU 30-month rule and the PAO versus best-before distinction.
- Wikipedia, “Period-after-opening symbol”. What the open-jar symbol is and how it is used.
- ISO 11930:2019, “Evaluation of the antimicrobial protection of a cosmetic product”. The standard challenge-test method used to support a PAO.
- Intertek, “Cosmetics Preservative Efficacy Challenge Testing”. What challenge testing involves and the standards labs test to.