What does the PAO symbol mean?

Look at the back or bottom of almost any cosmetic and you will find a tiny drawing of an open jar with a number next to it, like 6M, 12M or 24M. That is the Period After Opening symbol, usually shortened to PAO. It is one of the most useful things on the pack, and most people never notice it.

What the symbol means

The number is a count of months. The M stands for month. A 12M symbol means the product should be used within 12 months of when you first open it.

Fenty Beauty puts it plainly in its FAQ: if a product has a PAO of 12, it should be used within 12 months of opening. The clock starts when you open the product, not when you buy it or when it was made.

Where the symbol comes from

The symbol comes from European law. Article 19 of the EU Cosmetics Regulation (EC) No 1223/2009 splits products into two groups:

• Products whose minimum durability is 30 months or less must show a date of minimum durability, a best-before date.
• Products that last longer than 30 months show the open-jar symbol with the period after opening instead.

So when a product has a PAO symbol, it generally means it is stable for a long time sealed, but has a limited life once opened.

PAO vs the hourglass symbol

You may also see a small hourglass on some packs. Under the same EU rule, products that last 30 months or less show a best-before date, either with an hourglass symbol or with wording such as “best used before the end of.” That date applies whether or not you open the product.

So the two symbols answer different questions. The hourglass tells you when a product expires regardless of use. The open jar tells you how long it lasts once you start using it. A product usually carries one or the other, and if you ever see both, go with whichever date comes first.

What about products sold in the U.S.?

The U.S. works differently. The FDA says there are no U.S. laws or regulations that require cosmetics to carry expiration dates or specific shelf lives. You will still see the PAO symbol on many products in U.S. stores, because the same packaging is often sold in Europe too.

Sunscreen is the main exception. In the U.S. it is regulated as an over-the-counter drug and carries an expiration date. Brands such as The Ordinary say their sun protection products show an expiry date, while their other products rely on the PAO after opening.

How to use it

The symbol only works if you know when you opened the product. Three habits help:

1. Write the opening date on the pack with a marker, or on a small sticker.
2. Keep a list, on paper or in an app like Makeup Shelf.
3. Use our expiration calculator: enter the PAO and the date you opened it, and it gives you the date to replace it.

When the PAO isn’t the whole story

The PAO assumes normal use and storage. Heat, humidity, dirty brushes and fingers in jars all shorten a product’s life. A foundation left in a hot car or a cream used with unwashed fingers may go off long before its PAO.

So treat the PAO as the maximum, not a promise. If a product changes in smell, color or texture before then, replace it. Our guide on whether makeup expires lists the signs to look for, and our shelf-life guides show typical PAOs by product type.