What Does PAO Mean? (And What Is That Little Open Jar Symbol on Skincare) | Pandr

If you've ever turned a skincare product over and spotted a small icon of an open jar with a number inside it — that's PAO. It stands for Period After Opening, and it's one of the most useful (and most ignored) pieces of information on any beauty product.

Here's what it means and how to actually use it.

What PAO stands for

PAO stands for Period After Opening. It tells you how long a product remains safe and effective after you've opened it for the first time.

The symbol is a small open jar with a number and the letter M — for example, 12M means the product is good for 12 months after opening. 6M means six months. 24M means two years.

It's not the same as an expiration date. An expiration date refers to how long an unopened product stays stable. PAO kicks in from the moment you break the seal — which is why a product can be within its expiration date but still past its PAO if you opened it long ago.

Where PAO came from

PAO was introduced by the EU as part of its cosmetics regulations, applying to products with a shelf life of 30 months or more. According to cosmetic testing lab CPT, it first appeared in EU Directive 2003/15/EC and has been required on EU-market products since 2005.

In the US, the FDA does not require PAO labelling on cosmetics — it's voluntary. This is why some products, particularly American brands, may not have the symbol at all.

Why it matters

When you open a product, a few things start happening. Preservatives begin breaking down. Active ingredients like vitamin C and retinol start degrading with exposure to air and light. And each time you dip your fingers in or use an applicator, you're introducing bacteria into the formula.

Lab Muffin Beauty Science, run by cosmetic chemist and chemistry PhD Michelle Wong, notes that retinol products can decompose by more than half in the first six months after opening — and that's before the PAO is up. A vitamin C serum that's turned orange isn't just less effective — it may actively irritate skin.

For products without strong preservative systems — anything marketed as "natural," "preservative-free," or in jar packaging — the PAO window tends to be shorter and more important to follow.

What to do if there's no PAO

Some products, particularly those sold in the US or from smaller indie brands, won't have a PAO symbol. In that case:

Check for a batch code. Most products have a batch code printed on the bottom or back of the packaging. You can look this up using a free tool like CheckFresh or CheckCosmetic to find the manufacture date, which gives you a starting point.

Use your senses. A change in smell, texture, or colour is usually a reliable sign that something has turned. If a product that used to be white is now yellow, or a serum has separated, it's done.

Apply a general rule. If there's no PAO and you can't find a batch date, most opened skincare is best used within 12 months. Mascara and liquid eyeliner are shorter — three to six months. SPF products, which are regulated as drugs in the US and required to carry expiration dates, should always be used before that date.

A quick reference

| Product type | Typical PAO | |---|---| | Cleanser | 12 months | | Toner / essence | 12 months | | Vitamin C serum | 3–6 months | | Retinol | 6–12 months | | Moisturiser (pump) | 12 months | | Moisturiser (jar) | 6–12 months | | SPF | Per expiration date | | Mascara | 3–6 months | | Lip products | 12–24 months |

These are general guidelines — always defer to the PAO on the actual product if one is listed.

One practical tip

When you open something new, write the date on the bottom with a marker. You'll thank yourself in six months when you're trying to remember if that serum is still good. Certified Cosmetics has a good overview of what the symbol looks like across different packaging types if you're not sure what you're looking for.

Frequently asked questions

What is the little open jar symbol on skincare? That's the PAO symbol — Period After Opening. The number inside or next to it tells you how many months the product is safe to use after you first open it. A "12M" means 12 months, "6M" means six months, and so on.

What does 12M mean on skincare? It means the product is good for 12 months after opening. Once you've opened it, you have a year to use it before the manufacturer can no longer guarantee it's safe and effective.

What does the number on the bottom of my moisturiser mean? If it's next to a small open jar icon, it's the PAO — how long the product lasts after opening. If it's a longer code with no jar symbol, it's likely a batch code, which you can use to look up the manufacture date on CheckFresh.

Does skincare actually expire? Yes. Active ingredients degrade, preservatives break down, and bacteria can grow in opened products over time. Some products just become less effective past their PAO; others can cause irritation or breakouts. Either way, it's worth paying attention to.

What if my skincare doesn't have a PAO symbol? The PAO symbol is required in the EU but voluntary in the US, so some products — especially American brands — won't have one. Check for a batch code on the bottom of the packaging and use a free tool like CheckFresh to find the manufacture date. If you can't find anything, a general rule of 12 months after opening is a safe default for most skincare.

Is PAO the same as an expiration date? No. An expiration date refers to an unopened product — how long it stays stable sitting on a shelf. PAO starts from the moment you open it. A product can be within its expiration date but past its PAO if you opened it a long time ago.

Keeping track of PAO dates across a whole collection is one of the things Pandr is built to help with. Join the waitlist to be the first to try it.