The PAO Symbol & Best Before Dates on Cosmetics Explained

Two small symbols on a cosmetic label cause a surprising amount of confusion: the open-jar PAO symbol and the best-before date. Which one you need depends on how long your product lasts, and using the wrong one or both incorrectly is a common labelling error. This guide explains the durability rules clearly so you can label your products correctly.

This is one element of cosmetic labelling; for the wider set see our guides to ingredient lists and label warnings and mandatory statements.

Why cosmetics need durability labelling

Cosmetics do not last forever. Over time, preservative systems weaken, oils oxidise, textures separate and microbial protection can fail. Durability labelling tells the consumer how long the product remains safe and effective either before it is opened or once it has been opened. The rules give two tools for this, and which one applies depends on the product's minimum durability.

The deciding line is 30 months. If a product's minimum durability is 30 months or less, it needs a best-before date. If it is more than 30 months, it uses the period-after-opening (PAO) symbol instead. Understanding this split is the key to getting durability labelling right.

It helps to think of the two tools as answering different questions. The best-before date answers “how long is this product good for, sitting unopened on a shelf?” The PAO answers “once someone starts using it, how long does it stay good?” A short-life product needs the first; a long-life product, where the unopened shelf life is so long it is not the limiting factor, needs the second. Seen this way, the 30-month rule is less an arbitrary cut-off and more a sensible way of choosing whichever measure is actually informative for the product.

The best-before date (30 months or less)

If your product will keep for 30 months or less, you must show a date of minimum durability a best-before date. This is typically introduced with the wording “best used before end of” followed by the month and year, or shown alongside an hourglass/egg-timer symbol. It tells the consumer the date up to which the unopened product will perform as intended when stored properly.

Products with shorter shelf lives for example those with delicate natural preservative systems or fresh ingredients fall into this category. If storage conditions affect durability, the label should also indicate them, so the date is meaningful. The best-before date is about the product as a whole, regardless of when it is opened.

The PAO symbol (more than 30 months)

If your product lasts more than 30 months, you do not need a best-before date. Instead you use the period-after-opening (PAO) symbol the familiar open jar icon with a number of months inside or beside it, such as “12M”. This tells the consumer how long the product stays safe to use *after they first open it*: a “12M” product should be used within twelve months of opening.

The PAO recognises that a long-life product's clock effectively starts when air, water and skin first reach it. Choosing the right PAO figure is a judgement informed by the product's formulation and stability it is not a number to pluck at random and it should reflect how long the product genuinely remains good once in use.

When the PAO doesn't apply

There are sensible exceptions. The PAO symbol is not required for products where the concept of opening does not really apply single-use products, or products in packaging that prevents contact between the contents and the environment, such as a sealed pressurised aerosol. In those cases the open jar symbol would be meaningless, so it is omitted.

This is why you will not see a PAO on every product. The question to ask is whether “opening” meaningfully changes the product's safe life. If it does, and the product lasts over 30 months, the PAO applies; if opening is irrelevant or the product simply does not last that long, different rules take over.

How durability is decided

The minimum durability and any PAO are not guesses; they should be supported by evidence about how your product behaves over time stability and, where relevant, preservative efficacy. A water-containing product relies on its preservative system holding up; an anhydrous product depends more on its oils not going rancid. The safety assessment considers this, which is why durability labelling connects directly to your CPSR and the data in your Product Information File.

Setting a realistic shelf life protects both your customers and your brand. Claiming a longer life than the product can support risks selling a degraded product; setting it needlessly short wastes stock. Basing the figure on actual stability evidence gets the balance right.

Putting the date or symbol on the pack

However you express durability, it has to be clear and findable on the pack. A best-before date is commonly shown as a month and year, introduced by wording such as “best used before end of” or accompanied by the hourglass symbol, and it should be unambiguous   alone number that could be a date or a batch code is not good enough. A PAO is shown as the open-jar symbol with the number of months, such as “12M”, placed where the consumer can see it before and during use.

As with other label elements, durability information must be legible and durable in normal use, including in a steamy bathroom. If storage conditions materially affect how long the product lasts keep cool, keep out of sunlight those conditions belong on the label too, so the date or PAO is meaningful rather than misleading. A date that assumes ideal storage without saying so can give the consumer false confidence.

Durability labelling checklist

• Determine your product's minimum durability.

• 30 months or less → show a best-before date (with the hourglass symbol or “best used before end of”).

• More than 30 months → show the PAO open-jar symbol with months.

• Omit the PAO where opening is irrelevant (e.g. sealed aerosols, single-use).

• Base the figure on stability evidence, not guesswork.

• State any storage conditions that affect durability.

Frequently asked questions

What is the PAO symbol on cosmetics?

The period-after-opening symbol is an open-jar icon with a number of months, such as 12M. It tells consumers how long the product stays safe to use after it is first opened.

When do I use a best-before date instead of a PAO?

Use a best-before date when the product's minimum durability is 30 months or less. Use the PAO symbol when it is more than 30 months.

Does every cosmetic need a PAO symbol?

No. The PAO is omitted where opening does not affect the product, such as single-use items or sealed aerosols, and is not used on products that instead carry a best-before date.

How do I decide the number of months for the PAO?

It should reflect how long the product genuinely remains safe and effective after opening, based on its formulation and stability evidence not an arbitrary figure.

Who decides my product's shelf life?

It is determined from stability and, where relevant, preservative-efficacy evidence, and is considered within the safety assessment behind your CPSR and PIF.

What's the difference between the hourglass and open-jar symbols?

The hourglass (egg-timer) symbol accompanies a best-before date for products lasting 30 months or less. The open-jar PAO symbol, with a months figure like 12M, is for products lasting more than 30 months and refers to time after opening.

Do I have to print storage conditions too?

If storage materially affects how long the product lasts such as 'keep cool' or 'keep out of direct sunlight' those conditions should appear on the label so the date or PAO is meaningful rather than misleading.

References: Regulation (EC) No 1223/2009, Article 19 (EUR-Lex); Commission guidance on the period-after-opening symbol; UK Cosmetics Regulation as retained. General information only, not legal advice.