The Rising Symbols of EU Compliance - Part 3: Period After Opening

The European Union uses a range of symbols to signal product compliance, but perhaps none is as contentious as the open jar symbol, or alternatively, the period after opening (PAO), for cosmetic products. Its origin, as rumor has it, was itself the product of a somewhat sudden regulatory inspiration, and the developments that followed only added to the controversy, which may never produce a definitive consensus.

Yet despite the debates, the PAO has survived and functioned for decades, making it worth a closer look at how it came about, what it tells consumers, and why it remains relevant today.

For decades, cosmetics were largely judged on two things: whether they were effective and whether they were safe. The picture has since become considerably more complicated, with consumers and regulators increasingly also focused on other features such as organic origin, environmental footprint, and where the ingredients are sourced. That context matters when looking back at why the authors of EU cosmetics rules turned their attention in 2005 to product durability.

Previously, the system was relatively straightforward: If a cosmetic product had a minimum durability of more than 30 months, manufacturers were not required to display an expiry date. The regulatory change was introduced through the seventh amendment to the former EU Cosmetics Directive 76/768/EEC, rather than Regulation (EC) No 1223/2009 on Cosmetic Products (CPR), which later replaced the directive.

It sounded like a simple solution. Instead, it opened Pandora's box.

What Is PAO?

For cosmetics with a minimum durability of more than 30 months, an open jar symbol needs to be displayed on the packaging, accompanied by an indication of a safe period in months or years - for instance, “12M” means 12 months after opening. The PAO is not required where the concept of durability after opening is not relevant, such as for single-use products, products not at risk of deterioration, or products that do not open. In practice, the PAO should be supported by product-specific stability and safety considerations, including the formulation, packaging, intended use, and potential for deterioration after opening.

Minimum Durability

It is important to establish from the outset that shelf life is ultimately a scientifically supported estimate, rather than an absolute guarantee. For one, manufacturers cannot know exactly how or under what conditions a product will be used, requiring them to build a degree of worst-case thinking into their assessments to provide an adequate margin of safety.

A product can deteriorate in several different ways. In practice, manufacturers tend to focus primarily on two risks: microbiological contamination and the loss of the product's essential functionality, whether through separation, degradation of active ingredients, or other forms of instability. That does not mean, of course, other degradation factors should be ignored where they are relevant. However, the fact that the CPR itself puts these two factors at the forefront is telling.

Standardized Test Methods

The CPR requires the cosmetic product safety report to address microbiological quality and, where relevant, include preservation challenge-test results demonstrating adequate protection against microbial contamination. The regulation, however, does not prescribe detailed testing protocols, instead relying on recognized standards and industry guidance.

For stability testing, the main international reference is ISO/TR 18811:2018, which provides a framework for selecting appropriate methods without setting universal test conditions or acceptance criteria. The Cosmetics Europe/CTFA (Cosmetics, Toiletry, and Fragrance Association) industry guidelines provide additional practical clues on real-time and accelerated testing, including physical and chemical stability and product-packaging compatibility.

For microbiological protection, ISO 11930:2019 is the principal reference for preservation efficacy testing of products not considered microbiologically low risk. ISO 29621:2017 supports determining when a product may qualify as low risk, while ISO 17516:2014 sets microbiological quality limits for finished cosmetics.

In practice, companies must perform accelerated and heat-shocked stability and microbiological tests for cosmetic products in closed packaging, modeling conditions in which the products remain unopened and are stored under consistent conditions.

Ultimate Challenge of PAO

The concept behind the PAO is remarkably simple: Once a product is opened and used for the first time, the PAO is supposed to tell consumers how long it can continue to be used safely. So far, so straightforward. Determining that period, however, can be something of a nightmare.

Storage conditions matter even for a product sealed inside its packaging, although within reasonable limits the variables remain relatively manageable. Once the package is opened, however, the number of variables can become almost absurd. Does the consumer leave the jar open in a constantly humid bathroom? Is that bathroom in northern Sweden or Malta? Are clean hands going into the jar, or is the product being used on a farm where animals are present? The list could go on forever.

Accounting for that range of real-world conditions presents a formidable microbiological challenge. Against that backdrop - and given the limitations of the available testing standards - it is hardly surprising that many PAO periods tend to fall around six or 12 months. The appropriate period, of course, can vary significantly depending on the type of product.

Oddities at Regulatory Inspections

There are also exemptions from the PAO. If the product is single-use only, bears a “do not open” warning, or cannot be microbiologically compromised, such as nail polish removers, the PAO becomes obsolete.

These carve-outs, however, have become a recurring source of friction during regulatory inspections. While the case is clear-cut for some products, others face a higher bar in demonstrating that opening does not create a meaningful risk of deterioration. This judgment becomes even harder under the challenging assessment conditions described above, often leaving considerable room for disagreement between companies and regulators over whether an exemption is justified.

In some cases, the dispute may have less to do with the technical assessment itself than with actual consumer behavior. In one case involving hair dyes intended for single use, authorities requested a PAO after their surveys indicated that consumers were typically using the products more than once. The issue was further complicated by the fact that both single-use and multi-use hair dyes were available on the market, blurring the distinction regulators were seeking to draw.

The CPR does not explicitly prohibit companies from displaying both a minimum expiry date and a PAO on the same product, although from a practical standpoint, using both can create unnecessary complexity. In several member states, companies have nevertheless included both, often following pressure from national authorities.

That approach has created a new set of questions. If the minimum durability date and the period after opening point to different dates, which one should consumers follow? The issue also extends beyond consumer understanding. Retailers may be reluctant to accept products approaching their minimum expiry date, even where the PAO would allow the product to be used for considerably longer after opening. As a result, what began as a labeling and safety question can also become a commercial and supply-chain issue.

Endgame

If anything, the PAO has proved to be a remarkably resilient regulatory tool. An average bathroom may contain around 30 different cosmetic products, roughly half of them carrying a PAO symbol. Keeping track of when each one was opened can quickly become an administrative exercise in its own right, yet that is precisely what consumers would need to do for the labeling system to work as intended.

The persistent implementation challenges repeatedly put the PAO under scrutiny. Over the years, the requirement has faced criticism and even proposals for its removal, but it has survived each round of debate. For all its shortcomings, the open jar symbol has proved difficult to dislodge from the EU cosmetics framework. That regulatory staying power suggests the PAO is likely to remain a familiar feature of bathroom shelves for some time to come.

This is part of a series on the symbols used in EU compliance. Read the other articles in the seires for more information: The Rising Symbols of EU Compliance - Part 1: CE Marking, The Rising Symbols of EU Compliance - Part 2: UFI Code, and The Rising Symbols of EU Compliance - Part 4: Green Dot.

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