An expiry date, a manufacture date and a PAO symbol all say something different. This guide lays out what sets them apart against Korea's MFDS Cosmetics Act, with typical PAO by category and the signs a product has gone off.
Based on MFDS Cosmetics Act Article 10 · Updated May 2026
A cosmetic package carries markings like the expiry date, the manufacture date and the PAO symbol. Each one means something different. Read them wrong and you might toss a perfectly good product or keep using one that has gone off. This guide lays out what those markings mean, based on Korea's MFDS Cosmetics Act Article 10 and its enforcement rules.
Three markings — what sets them apart
Marking
Meaning
Required?
Manufacture date
The date the product was made
Required (may be waived if an expiry date is shown)
Expiry date
The last date the product is safe to use while unopened
Required (may be waived if a manufacture date is shown)
PAO (Period After Opening)
How many months the product lasts once opened
Not required (many brands print it voluntarily)
Korea's Cosmetics Act requires either a manufacture date or an expiry date (Enforcement Rule Article 19). PAO is not mandatory, yet many products print it under the influence of EU rules.
Reading the PAO symbol
PAO (Period After Opening) shows a number and a unit inside an open jar symbol. The M stands for Month.
6M12M24M36M
6M means use within six months of opening, and that mostly covers mascara and eyeliner.
12M means use within twelve months of opening, typically liquid foundation or lipstick.
24M means use within twenty-four months of opening, usually toners and creams.
36M means use within thirty-six months of opening, which covers some powder products.
One thing to watch: the PAO clock starts the moment you open the product. If you kept it sealed for a year and opened it only then, the PAO begins on that opening day. The expiry date still applies on its own, even while the product sits unopened.
Typical PAO by product category
Below are average voluntary PAO figures for products on the Korean market. Real products vary, so the label always comes first.
Category
Typical PAO
Signs it has gone off
Toner
12-24M
Cloudiness or sediment, a sour smell
Essence / Serum
12-18M
Color change (vitamin C browning in particular), separation
Cream / Lotion
12-24M
Layers separating, a sheen on the surface, a rancid smell
Sunscreen
12M (within the unopened expiry date)
Layers separating, possible drop in protection
Mascara / Eyeliner
3-6M
Clumping, a sour smell, stinging
Liquid foundation / BB cream
6-12M
Layers separating, color shift
Lipstick / Lip balm
12-24M
Crystals or an oily film on the surface, rancidity
Powder makeup
24-36M
A hardened surface, mold
Shampoo / Body wash
12-24M
Separation, a change in thickness, mold
Six signs a product has gone off
Even within the use-by window, stop using a product if any of these show up.
Color change. The shade deepens or browns from its original color. A vitamin C serum that turns brown or orange is a sign oxidation has set in.
Separation and sediment. The product no longer mixes back together when you shake it, which means its emulsion stability has broken down.
An off smell. A sour, rancid or moldy smell that is clearly different from the original scent.
A change in thickness. The product turns watery or hardens.
Surface sheen and an oily film. In creams, the oil rises and floats on top.
Skin irritation. A product you always got on with suddenly brings stinging, redness or itching.
Storing cosmetics — tips to make them last
Keep away from direct sun and heat: store glass bottles in a drawer out of sunlight. Bathrooms run humid, which suits some products poorly.
Keep caps and pumps clean: use a spatula so your fingers do not touch the product directly, and wipe the pump nozzle now and then.
Oxidation-sensitive products like vitamin C: pick ones in dark containers and use them up fairly quickly after opening.
Whether to refrigerate: natural or preservative-free products may call for the fridge, while ordinary cosmetics hold their emulsion better at room temperature. Follow the label.
Labels on cosmetics bought overseas
When you buy from overseas, the labeling can differ from Korea's standards.
The EU and UK require an expiry date on products lasting under 30 months, and let products lasting 30 months or more show only a PAO (Cosmetics Regulation 1223/2009).
The US sets no expiry-labeling requirement for ordinary cosmetics, and reserves it for OTC products such as sunscreen and acne treatments.
Japan can waive the marking where stability is proven for three years or more.
Products bought from overseas often have less time left on the expiry date than ones sold through official Korean channels, so it is worth checking before you buy.
Editorial Tip
Note the opening date
"Because the PAO starts the day you open a product, it helps to mark the month you opened it with a small dot inside the cap or on the label. Three numbers cover most of it: 6M, 12M and 24M."
— Beauty Dupe Editorial
Frequently asked questions
My mascara is marked 6M. Can I keep using it past six months?
Mascara touches the eye area, so it calls for the most caution. Once the six-month PAO passes, the risk of bacterial growth climbs and with it the chance of conjunctivitis or a stye. It is best to stick to the PAO here.
If only a manufacture date is printed, how long can I use the product?
Korea's MFDS treats 36 months (three years) after manufacture as the general safety window for products marked with a manufacture date. That figure assumes the product is unopened, though. Once you open it, follow the PAO instead.
What happens if I use a product past its expiry date?
In most cases the product loses potency, bacteria multiply and oxidation byproducts build up. Reactions range from mild irritation to allergy or contact dermatitis.
Do samples follow a PAO too?
Yes. A sample of the same formula carries the same PAO. For one or two-use samples designed to be single use, it is best to apply them right after opening.
Skin Warning
A product that has gone off can bring anything from ordinary irritation to allergy or contact dermatitis. If you notice separation, an off smell or sudden irritation, stop using it right away.
Sources
Korea Ministry of Food and Drug Safety — Cosmetics Act Article 10 (Labeling and Marking)
Korea Ministry of Food and Drug Safety — Cosmetics Act Enforcement Rule Article 19 (Method of Labeling and Marking)
Korea Ministry of Food and Drug Safety — Guidelines for Monitoring Adverse Reactions After Cosmetic Use
EU Cosmetics Regulation (EC) 1223/2009
U.S. FDA — Cosmetic Shelf Life
Disclaimer · This guide is general information. For the exact PAO and expiry date of any individual product, always check the product package.
