Cosmetic packaging may carry two separate pieces of time information: the expiry date of the unopened product and the PAO, which shows how long the product can be used once it has been opened. Mixing the two up can lead you to use a cream that has been open for months, or an old mascara, for longer than you should.
In short: PAO (Period After Opening) shows how many months a product can be used after it has been opened; “12M” next to the open-jar symbol means 12 months from first opening. The expiry date, on the other hand, applies to the unopened product. If the colour, smell or texture changes, stop using the product before the period is up. As the FDA reports, manufacturers recommend throwing mascara away two to four months after purchase; for Power De-Puff Girls, the PAO is 12 months.
What is PAO, and what does 12M mean?
PAO stands for “Period After Opening”, the length of time a product can be used once it has been opened, and it is shown on the packaging as a drawing of a jar with its lid open. The number written on or next to the drawing is the number of months; “M” is short for the English word “month”. “6M” means six months, “12M” twelve months and “24M” twenty-four months.
The period starts from first opening, not from the day of manufacture or purchase; the symbol does not give a date, so you need to note the day you opened the product yourself. The rest of the label carries the ingredient list and the manufacturer's claims: the order of the list and the meaning of the names are explained in the guide to reading an INCI list, and what a claim such as “vegan” does and does not cover is explained in our article on the definition of vegan cosmetics and label claims.
What is the difference between the expiry date, shelf life and PAO?
The expiry date shows how long the closed product lasts and PAO how long the opened product lasts; shelf life is the general concept of durability behind both.
| Term | What question does it answer? | On the packaging |
|---|---|---|
| Shelf life | For how long does the product look and work as expected and remain safe to use? | Not stated directly; the manufacturer determines it according to the type of product, its use and storage |
| Expiry date | Until what date can the closed product be used? | As a date |
| PAO | For how many months can the opened product be used? | Open-jar symbol and a number of months such as “12M” |
The U.S. Food and Drug Administration (FDA) considers determining shelf life to be the manufacturer's responsibility; some manufacturers determine it by keeping product samples under different temperature and humidity conditions.
Why do opened cosmetics go off?
Each time an opened product is used, it comes into contact with fingers, applicators, air, light and heat. The main causes listed by the FDA:
- Dipping your fingers into a product introduces bacteria, mould and yeast; preservatives keep these under control, but preservatives can break down over time.
- Applicators, especially mascara brushes, come into contact with microorganisms every time they are used.
- Damp places such as bathrooms can make it easier for microorganisms to grow.
- Emulsions, which are mixtures of water and oil, can separate; the product can dry out and harden.
- Temperature changes, sunlight and air can cause changes in colour, texture and smell.
In a study that examined cosmetics unopened, in use and nearly finished, contaminated products were relatively rare, and the contamination reported was in cleansing products such as bubble bath, shampoo and liquid soap; even so, the authors noted that some products were unable to suppress the growth of microorganisms and that this posed a potential health risk.
How can you tell that an opened cosmetic has gone off?
A clear change in colour, smell or texture is a sign to stop using the product, even if its PAO period has not ended. Checklist:
- Has the colour darkened or changed?
- Does it smell different from the day you first opened it?
- Have the water and oil phases separated, or has the texture become lumpy or watery?
- Has the product dried out, hardened or cracked?
How does the type of packaging affect the hygiene of an opened product?
The way a product is taken out of its packaging determines how much contact with fingers, air and light the contents get each time you use it. Three packaging examples from s'hevec products:
| Packaging | s'hevec example | After opening |
|---|---|---|
| Frosted glass jar | Any Time Of Day Water-Based Moisturising Cream | Each time you open the jar, the cream is exposed to air, and to your fingers as you take some out. Use a spatula or freshly washed and dried fingers, close the lid straight away and keep the jar in a cool, dry place. |
| Amber glass pump bottle | Glow Me Like You Do Vitamin C Serum | With a pump, you do not need to touch the product with your fingers; amber glass limits light and air. Store in a cool, dry place away from direct sunlight. |
| Tube | Firm Baby Firm | You do not reach into the cream as you would with a jar; do not let the tip of the tube touch your skin, and do not leave the cap off. |
The Ethyl Ascorbic Acid (3-O-ethyl ascorbic acid) in Glow Me Like You Do is a stable vitamin C derivative; we cover how these derivatives differ from ascorbic acid and how to store them in our article on vitamin C derivatives and storage. For how long each of these products can be used after opening, go by the symbol on its own box.
How long can eye-area products be used after opening?
Eye-area products generally have a shorter period of use than other cosmetics; the FDA notes that expired eye-area products can lead to infected eyes and that this can be serious. Manufacturers recommend throwing mascara away two to four months after purchase, because the brush comes into contact with bacteria and fungi every time it is used. Do not moisten mascara that has dried out with water or saliva, as this introduces bacteria into the product; if it has dried out, throw it away.
Power De-Puff Girls Eye Serum carries the 12M symbol; the order of application and its use after opening are covered in the guide to using a caffeine eye serum.
How should cosmetics be stored?
According to the FDA, how long you can safely use a cosmetic also depends on your habits; a product left in the heat can go off before the end of its PAO. To keep track of the opening date:
- On the day you first open the product, write the date on the box or on the bottom of the packaging.
- Add the number of months shown on the symbol to that date and note the end month as well.
- When the end month arrives, replace the product even if it looks unchanged.
The FDA's recommendations for storage:
- Do not leave products in places exposed to heat, such as a hot car; heat can cause preservatives to break down and microorganisms to grow faster.
- Do not leave sunscreen containers in direct sun; if you will be outdoors in the heat for a long time, wrap them in a towel or keep them in the shade.
- Keep containers and applicators clean; do not share make-up.
When should you see a doctor?
If your eye is infected, see your doctor. In that case the FDA recommends consulting a healthcare provider, stopping all eye-area cosmetics and throwing away the products you used while your eye was infected.
Frequently asked questions
How long does an unopened cosmetic last?
It varies by product; for a closed product, check the expiry date on the packaging. According to the FDA, expiry dates are not a legal requirement for cosmetics in the US; products with an SPF claim, however, are also regulated as drugs, so they are subject to stability testing and must carry an expiry date on their labels.
Can you use a cosmetic after its expiry date?
No. As the FDA points out, preservatives can break down over time and allow bacteria and fungi to grow. Throw away an expired product even if it looks unchanged.
What should I do if I don't remember when I opened a product?
First check its colour, smell and texture; if anything has changed, do not use it. If nothing has changed but you think the product has been open for a long time, replacing it is the better choice.
Is it safe to use testers in shops?
According to the FDA, testers in shops become contaminated more easily than the same product at home. If you need to try one, use a new, unused applicator, such as a clean cotton bud.
Can you use cosmetics that are second-hand or bought from an unreliable source?
The FDA advises caution with products resold at flea markets or online; they may be past their shelf life, used, diluted or counterfeit. If the safety seal is broken, there is no way of knowing when the product was opened.
Sources
- U.S. Food and Drug Administration (FDA). Shelf Life and Expiration Dating of Cosmetics.
- Campana R et al. Microbiological study of cosmetic products during their use by consumers: health risk and efficacy of preservative systems. Lett Appl Microbiol. 2006.
- U.S. Food and Drug Administration (FDA). Sunscreen: How to Help Protect Your Skin from the Sun.
This content is for information only and does not replace medical advice. s'hevec products are cosmetic products and are not intended for medical treatment. It was prepared by the s'hevec Team on the basis of the s'hevec product data library and the sources listed above.
