Beauty Products: Batch Codes, Expiry and Skin Compatibility

Two different dates, often confused

Cosmetics and skincare carry more than one kind of date-related marking, and the two most common ones answer different questions: how long the product lasts once opened, and, separately, how long it is expected to remain stable while still sealed. Knowing which symbol is which makes it easier to judge whether a discounted item is simply good value or is being sold cheaply because it is close to the end of its usable life, which is a distinction a voucher code or coupon code does not change either way.

The open jar symbol, or PAO mark

Under EU cosmetics regulation, retained in UK law after Brexit in much the same form, a product with an expected shelf life of more than 30 months does not need a fixed best-before date. Instead, it carries a small open jar icon with a number followed by an M, for example 12M or 24M, known as the Period After Opening mark. This states how many months the product is considered safe and effective to use once opened, counted from the date it is first used, not from the date of manufacture or purchase. A jar of face cream marked 12M is intended to be used up within twelve months of opening it, regardless of how long it sat sealed on a shelf beforehand. Products expected to last less than 30 months, such as some formulations without stabilising preservatives, instead carry a fixed best-before date rather than a PAO symbol.

Batch codes: not the same as a date

Separately from the PAO mark, most cosmetics carry a batch code or lot number, a short string of letters and numbers stamped or printed on the packaging that identifies the specific production run. A batch code is primarily there for traceability, so a manufacturer can identify affected stock in the event of a quality issue or recall, and it is not, on its own, a readable date. Some manufacturers encode a production date within the batch code using their own internal format, and third-party batch code checkers exist for some brands, but there is no universal standard across the industry, so a batch code should be treated as a traceability reference rather than a way to calculate a product's age without further information.

How this differs in the US

The US Food and Drug Administration does not generally require an expiry date on cosmetics, unlike the EU and UK system, though some product categories regulated as over-the-counter drugs, such as sunscreen, do carry a mandatory expiry date under separate rules. Many manufacturers selling internationally add a PAO symbol and batch code to US-market packaging voluntarily, to keep labelling consistent across regions, but a US-only product may show neither a fixed expiry date nor a PAO mark, which makes checking the batch code and, where possible, the manufacturer's own guidance more relevant for anyone trying to judge freshness on a US purchase.

Skin compatibility and patch testing

Reactions to a new cosmetic or skincare product are usually specific to an individual's skin rather than a sign the product itself is faulty, which is why a small patch test on an inconspicuous area of skin, left for a day or two before wider use, remains a reasonable precaution for any new product, and particularly for anything left on the skin for an extended period, such as a moisturiser or a fragranced product. The full ingredients list, printed using standardised INCI names, is the most reliable way to check for a specific known allergen or an ingredient to avoid, and EU and UK labelling rules require certain fragrance allergens to be listed separately once they exceed a set concentration, precisely so this check is possible without contacting the manufacturer.

What buying online changes

• Storage conditions before dispatch are not visible to the buyer, and heat or direct sunlight during transit or warehousing can shorten a product's effective life even within its stated dates.
• A steep discount on a beauty product close to its PAO or best-before date is not necessarily a problem if it will be used promptly, but it is worth checking the marking before assuming the discount is simply generosity.
• Genuine sets from an authorised retailer carry consistent, legible batch codes; packaging with a scratched-off or missing batch code is a reasonable reason to buy elsewhere.

Comparing retailers once the check is done

Once a product's dates and ingredients look right, comparing price across retailers and checking for a current code is the sensible next step. We check codes across 527 shops in 22 countries several times a day, with no account or cookies required, and current listings for beauty retailers sit under Health & Beauty for UK-based shops or the matching US category for a US-based retailer.