PAO Symbol (12M) on Skincare: What Does It Mean?

Turn over almost any jar of moisturizer or tube of cleanser and you’ll spot a tiny drawing of a pot with its lid off, next to a number and the letter M: 6M, 12M, 24M. That little open jar is the PAO symbol, short for period after opening, and it’s one of the most useful markings on your skincare. It tells you how long a product is meant to stay at its best once you’ve opened it.

Here’s what the PAO symbol means, where it comes from, how to work out your product’s real “use by” date, and the signs that mean it’s time to say goodbye sooner.

Key takeaways

• The PAO symbol is an open jar with a number and “M”. The number is how many months the product is meant to be used after you first open it.
• The clock starts on the day you open it, not the day you buy it, so note that date.
• If there’s also a printed best-before date, follow whichever date comes first.
• Changes in smell, color or texture mean it’s time to toss a product, even if it’s still “in date”.
• The symbol comes from EU cosmetics law and isn’t required on US cosmetics.

What the PAO symbol means

The number beside the open jar is a count of months. “12M” means 12 months after opening, “6M” means six, and so on. Some labels show the period in years instead, which the rules also allow.

Why does opening a product change anything? From the first time you twist the cap, a formula is exposed to air, light, warmth and whatever is on your fingers or brushes. Dermatologists at the American Academy of Dermatology (AAD) explain that cosmetics break down over time, and that with use, germs can build up in them. Preservatives and clever packaging slow this down, but they can’t hold it off forever. The PAO is the manufacturer’s guide to how long the product can be used safely once it’s open.

Where the PAO symbol comes from: EU cosmetics regulation

The open-jar symbol is set out in the European Union’s cosmetics law, Regulation (EC) No 1223/2009. Article 19 of that regulation covers labeling, and it works like this:

• Products expected to last 30 months or less must show a date of minimum durability. That’s the date until which the product, stored properly, keeps doing its job. It’s shown with a small hourglass symbol or the words “best used before the end of”.
• Products expected to last more than 30 months don’t need a printed date. Instead, they must show how long the product can be safely used after opening, using the open-jar symbol followed by the number of months and/or years. The only exception is where the idea of “after opening” isn’t relevant to the product.

That’s why so many products carry only the open jar and no date: under EU rules, their unopened shelf life is long enough that the period after opening is the more useful information. You’ll also see the symbol in the UK. The NHS, for example, tells people to check the open-jar mark on their sunscreen.

In the United States things are different. The AAD notes that period-after-opening information isn’t required on cosmetics there, and that you probably won’t find an expiration date on most makeup either. Some products sold in the US still show the open jar, but if yours doesn’t, you’ll need to keep track yourself. (Sunscreen is a special case in the US: it’s regulated as an over-the-counter drug and often has an expiration date printed on the pack.)

How to calculate a best-before date from the PAO

Working out your product’s real “use by” date takes a few seconds:

1. Note the day you open it. Write it on the label with a permanent marker, or log it in an app.
2. Add the PAO months. Opened on 15 March 2026 with a 12M symbol? Plan to finish it by 15 March 2027.
3. Check for a printed date. If the pack also shows a best-before date, compare the two and go with whichever comes first.
4. Watch out for short months. Open something on 31 August with a 6M symbol and there’s no 31 February to count to. The sensible answer is the last day of February.

Here’s how that looks with a few everyday examples:

Opened	PAO	Printed best-before	Use by
15 Mar 2026	12M	None	15 Mar 2027
1 Oct 2026	12M	End of June 2027	End of June 2027 (printed date comes first)
31 Aug 2026	6M	None	28 Feb 2027
10 Jan 2026	24M	End of May 2026	End of May 2026 (printed date comes first)

The last row is the one people often miss. A generous PAO doesn’t extend a product past its printed date. If a cream has been sitting in a drawer for ages before you open it, the best-before date may arrive long before the PAO does.

When to throw a product away, even before the date

The PAO assumes the product has been stored and used sensibly. Heat, steamy bathrooms, open lids and shared applicators can all shorten a product’s life. The AAD suggests tossing a product once it has:

• Gone clumpy (mascara and eyeliner are the usual suspects)
• Separated or changed texture, like a foundation that splits into layers
• Started to crumble or break apart, like an old powder blush
• Developed an off smell
• Turned dry and flaky, or unusually runny
• Changed color
• Started to feel different when you put it on

Dermatologists also recommend throwing away any eye makeup you used while you had an eye infection.

Why does this matter? According to AAD dermatologists, old or expired products may irritate your skin, and over time bacteria and mold can grow in them. That can lead to eye infections or skin infections such as impetigo or folliculitis. For products with a job to do, like sunscreen, an old formula may simply not protect you the way the label promises.

What if there’s no PAO symbol at all?

If a product is unopened and has a printed date, go by that date. If there’s no date and no open jar, write the opening date on it and follow general guidelines for that type of product. Dermatologists recommend replacing mascara and liquid eyeliner every three months, for example. We’ve put together a product-by-product list in how to tell if your skincare or makeup has expired.

Simple habits that help products last

A few small habits can help a product make it all the way to its PAO date:

• Store products somewhere clean and dry, at room temperature and out of direct sunlight.
• Wash your hands before dipping into jars, or use a clean spatula.
• Close caps and lids tightly after every use.
• Keep brushes and sponges clean, and don’t share products you apply to your skin or eyes.
• Keep an eye on products you only use occasionally. They’re the ones most likely to quietly pass their date.

How Skinchii calculates PAO for you

Keeping track of opening dates for a whole shelf is exactly the kind of admin that’s easy to forget, so Skinchii does the math for you. When you add a product to your shelf, you can enter the date you opened it, choose its period after opening (3, 6, 9, 12, 18, 24 or 36 months) and add any printed expiry date. Skinchii works out the after-opening date, handles short months like February for you, and uses whichever date comes first as the product’s use-by date, the same rule described above.

From there, products that are close to their date show up in the app’s Expiring soon and PAO guidance lists, and expired ones get their own list so they don’t sneak back into your routine. Alerts arrive ahead of time. By default that’s 30, 14, 7 and 1 day before, and you can choose your own reminder days and quiet hours. When you scan a product’s barcode or pick it from the catalog of 4,500+ curated products, Skinchii can fill in its details, including the PAO when the catalog knows it.

Want a cute little buddy that remembers opening dates so you don’t have to? Skinchii is coming soon to iOS and Android. Join the waitlist to be first in line.

Sources

• European Union: Regulation (EC) No 1223/2009 on cosmetic products, Article 19 and Annex VII (consolidated text)
• American Academy of Dermatology: When to toss your makeup and sunscreen
• NHS: Sunscreen and sun safety
• U.S. Food and Drug Administration: Sunscreen: How to help protect your skin from the sun

This article is for general information and isn’t medical advice. For persistent skin concerns, see a board-certified dermatologist.