The Period After Opening symbol is the open-jar pictogram that appears on most cosmetic packaging in the EU and UK. Inside the jar, a number followed by the letter M (for example 6M, 12M, 24M) tells the consumer how many months the product remains safe and fit for use once the container has been opened for the first time.

The obligation sits in Article 19(1)(c) of Regulation (EC) No 1223/2009 on cosmetic products, retained in the UK by the Schedule 34 amendments to the Cosmetic Regulation. The PAO is set by the Responsible Person on the basis of stability data, preservative efficacy (challenge) tests and the way the product is packaged and used, not by marketing or convenience.

The two marks are mutually exclusive. PAO is required when the product's minimum durability is more than 30 months. When the minimum durability is 30 months or less, the product must instead carry a best-before date, shown by the hourglass symbol or the wording "best used before the end of" followed by the date.

In practice, leave-on products in stable formats (creams, lotions, serums in airless or tube packaging) usually exceed 30 months and carry PAO. Mascara, liquid foundation, sunscreens, fresh or preservative-free formulas and some natural products often sit under 30 months and carry the hourglass instead. A product must never carry both.

Annex VII of the Regulation sets out a small set of cases where PAO is not required because the concept is meaningless: single-use products (single-dose sachets), products whose packaging does not allow consumer contact with the formula (sealed aerosols, true airless dispensers under specific conditions), and products where there is no realistic risk of deterioration once opened.

The exemption is narrower than it looks. Many brands assume their airless pump qualifies, when the regulator's test is whether the consumer can in fact touch the formula. If the formula can be reached, PAO applies, even if the dispenser is well designed.

PAO is a finding, not an opinion. It is set by the Responsible Person (or US Responsible Person under MoCRA, where applicable) and recorded in the product information file (PIF) and the cosmetic product safety report (CPSR). The inputs are real-time and accelerated stability data, preservative efficacy testing (typically ISO 11930), packaging compatibility and a realistic view of how the consumer will use the product.

The CPSR must justify the PAO. A 12M PAO on a water-based emulsion with no challenge test or with weak preservation is the kind of gap that authorities flag in market surveillance. The same PAO must be reflected on artwork, in any retailer technical files, and in customer-specific product specifications.

For a brand with dozens or hundreds of SKUs, PAO is not a one-off artwork decision. Every reformulation, every packaging substitution, every new market launch can change the answer. A new fragrance, a switch from a tube to a jar, a change in preservative system, all of them can move the PAO and need to flow through to artwork, CPSRs, notifications (CPNP in the EU, SCPN in the UK) and retailer data sheets.

Worldover treats PAO and minimum durability as structured properties of the SKU, linked to the underlying stability and challenge test data. When the formula or packaging changes, the system flags every downstream artefact that needs updating, so the right symbol and number reach the consumer on every market.