Skincare products have expiry information, but it appears in two different forms that mean different things and are regulated separately. Many people either ignore this information entirely or confuse the two systems. Understanding both allows you to use products safely and know when it is time to let go of something, which matters more in natural skincare than most people realise.
The best-before date
A best-before date on skincare appears as an hourglass symbol followed by a date (format: month/year). In EU cosmetics regulation, a best-before date is required for products with a shelf life of 30 months or less. Products with a longer unopened shelf life (most stable conventional products) do not legally need to display a best-before date, though they may choose to.
The best-before date refers to how long the product remains safe and effective in its unopened state, stored under appropriate conditions. After this date, the manufacturer cannot guarantee the product’s safety or efficacy. This is relevant for products bought and kept in storage before use: if you stock up on sale and the products sit unused for a year, the best-before date tells you whether they are still usable when you eventually open them.
The PAO (Period After Opening) symbol
The PAO is the open jar icon with a number followed by “M” (for months). This is the more practically relevant symbol for daily use. It indicates how long a product is safe and effective after opening, regardless of the manufacture date or best-before date.
A “12M” symbol means the product should be used within 12 months of first opening. A “6M” symbol means six months. Typical PAO periods by product type:
- Water-based serums and toners: 6-12 months
- Face creams and moisturisers: 12 months typically
- Facial oils and anhydrous products: 6-12 months (oxidation rather than microbial growth is the concern)
- Sunscreens: 12 months, and often have a specific date printed
- Mascara and eye products: 3-6 months (microcontamination risk is higher with eye products)
- Natural cosmetics with milder preservative systems: often shorter PAO periods, sometimes as short as 3-6 months
Why natural cosmetics often have shorter PAO periods
Conventional cosmetics preserved with broad-spectrum synthetic preservatives (paraben combinations, phenoxyethanol at effective concentrations, isothiazolinone compounds) can maintain microbial stability for 24-36 months after opening. Natural preservation systems, using vitamin E, rosemary extract, essential oils with antimicrobial activity, or fermentation-derived acids, are effective but often have a narrower window of stability.
This is not a defect in natural cosmetics; it is a consequence of genuinely gentler preservation. The trade-off is that natural products need to be used within their PAO period more strictly than their conventional counterparts, and storage conditions matter more.
For products made in small batches without the exact preservative load of mass-market products, the PAO period also reflects that a smaller batch size means the product has not been through the same extended stability testing that larger producers run. A reputable natural cosmetics brand sets PAO periods based on tested stability data, but may default to more conservative periods as a result.
How to track your PAO in practice
Write the opening date on the bottom of each product when you first use it. A small permanent marker takes five seconds and removes all guesswork. Alternatively, a small label on the back. Knowing when you opened a product is the only way to accurately use the PAO.
Check your shelf or cabinet periodically. Products with 6M PAO that you opened six months ago but are only half used need to be assessed: are they still within their safe window? A product with changed smell, colour, texture, or consistency should be discarded regardless of the PAO date, because these changes indicate degradation.
Signs a product has expired or degraded
Changed smell: rancid, fermented, sour, or off odours that were not present originally. For facial oils, a crayon-waxy smell indicates oxidation. For water-based products, a sour or fermented smell indicates microbial growth.
Changed colour: significant darkening of a vitamin C product indicates oxidation of L-ascorbic acid. Unusual colour changes in creams or serums can indicate degradation or contamination.
Changed texture: unexpected separation (especially in emulsions that were previously uniform), graininess in products that were smooth, unusual stickiness or runniness.
Visible contamination: mould or any floating particles not present originally. This is an unambiguous reason to discard immediately.
The consequences of using degraded cosmetics range from reduced efficacy (lost active ingredients) to skin irritation (breakdown products of rancid oils or degraded preservatives) to potential infection (microbially contaminated products, particularly for eye products). None of these are acceptable risks for products meant to benefit skin.
Extending shelf life within the PAO window
Store products away from direct sunlight and heat. The bathroom is often the worst location for sensitive products (humidity from showers, temperature fluctuations). A cool, dry shelf or drawer is better for most products. Refrigeration significantly extends the effective life of unstable actives (vitamin C, retinoids, high-linoleic oils). Keep lids closed tightly after use. Use pumps or spatulas rather than fingers dipping into jar products to reduce contamination.
Using products within their PAO is not fussiness; it is using products as they are intended to be used, at the effectiveness and safety level for which they were formulated and tested.