Period After Opening (PAO)

Period After Opening (PAO)

Under EU regulations (Article 19, Reg 1223), cosmetic products with a shelf life of more than 30 months do not require an expiry date. Instead, they must display a Period After Opening (PAO) symbol indicating how long the product remains safe for consumer use once opened.

Why PAO Matters

  • Consumer Safety: Helps users understand how long a product stays fresh and non-hazardous after initial use.
  • Regulatory Requirement: Compliance with both UK and EU standards when a “best-before” date isn’t required.
  • Brand Assurance: Demonstrates that you’ve validated the quality and longevity of your product, earning consumer trust.

Our Approach

We combine multiple test methods to confirm a product’s safety over its claimed PAO:

  • Microbial Limits: Evaluates baseline contamination levels to ensure they remain within safe parameters.
  • Stability Testing: Includes both real-time and accelerated studies to identify any gradual changes in performance or composition.
  • Preservative Efficacy (Challenge) Tests: Confirms the formulation can resist microbial spoilage throughout its intended lifespan.
  • Simulation Tests: Recreates actual usage conditions to validate how the product stands up to repeated opening and exposure.
  • Risk assessment & Data Review: If you already have existing test data, our team can review and provide a probable PAO recommendation, saving time and resources.

This comprehensive strategy helps pinpoint the maximum length of time a product can be safely used—providing you and your customers with confidence in its post-opening shelf life.

Partner with MSL for PAO Evaluation

Our experienced team guides you through each stage of testing, ensuring your product meets all regulatory requirements for PAO labelling. By entrusting MSL, you’ll have reliable, data-driven support for your product’s safety and longevity.

For more information or to discuss how we can help validate your PAO claims, contact us. We look forward to helping you deliver high-quality, compliant cosmetics to the market.