How to Check Skincare Expiry and the PAO Symbol

Skincare does not last forever. Two key indicators tell you when to replace a product: a printed expiry or best-before date, and the period-after-opening symbol that indicates how long it stays good once opened.

Reading the PAO Symbol

The period-after-opening (PAO) symbol is a small open-jar icon with a number and the letter M, such as '12M', meaning the product is intended to be used within twelve months of opening. It assumes you opened it around the time of purchase, so noting the date you open something helps you track it.

Expiry and Best-Before Dates

Some products also carry a printed expiry or best-before date, which is especially relevant for those with active ingredients or limited shelf stability. Once a product is past its date, its actives may be less effective and the formula may be more prone to spoilage.

Trust Your Senses Too

Beyond the printed dates, watch for changes in color, smell, or texture, or separation that will not mix back together; these can signal a product has gone off, even before its date. Discard anything that looks or smells wrong. Storing products well, away from heat and light, helps them reach their intended lifespan.

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Sources

• Shelf life - Wikipedia ↗

✍️ Written & reviewed by the KoreaPlus Editorial team — dermatologist-informed, cosmetic-science researched & source-cited. Last reviewed 2026-06-21.

General educational information using cosmetic structure-function wording — not medical advice. Always patch-test new actives. © KoreaPlus.