When using beauty products, do you ever really stop to think about how old they are? When you’re in the routine of applying a certain amount of makeup from certain containers in a certain order, you don’t really think about the makeup’s presence, except when it runs out. But a large container won’t run out quickly, and the makeup may well be expired long before you run out. It’s important to track the expiry dates of your products to prevent yourself from using outdated, possibly dangerous or irritating chemicals.

Most products have a date of manufacture stamped on them. It could be anywhere on the packaging or container, and will appear as an odd string of numbers or letters (or both). Once you have found this string, if you can’t decode it easily, look up online the manufacturer’s system for determining the expiry date, or email the company and ask. If there’s no date, the longest you should keep the product around is three years. By that time, there’s a good chance it will have “gone strange” or be germ-laden, so you should definitely replace products older than this.

Eye products should obviously be kept as clean as possible, and not for too long. Four months is the longest you should keep mascara, and possibly less time. Three years is the maximum for most eyeliner pencils, but it’s good to check your specific kind of eyeliner, as liquids will not last as long as pencils without being risky.

Be careful with facial products: no more than a year for concealer, two years for powder, a year to eighteen months for foundations (oil-based foundations last longer), and a year for blush. Again, look at the manufacturing codes to see when it was made, then calculate the expiry date from that day forward.

Other beauty products with expiration dates include nail polish, which should be tossed a year after opening it, and around a year for for other skin products. Perfumes are another commonly ignored item when it comes to expiry dates; don’t use the product for more than two years.

To increase the length of time you can use a product, try not to expose it to the air or germs in the environment. This means not leaving products open on the counter, pumping the mascara wand in and out of the container, or dropping things on the floor. Don’t share your makeup with others if at all possible, as this can greatly increase the risk of germs spreading between you and misuse of your products by others who don’t know better. Finally, application tools are not exempt from these rules: wash sponges weekly and don’t keep them around and in service for more than a month.

You can try labeling beauty products with their expiration dates if you don’t think you will remember when the time comes around, or write the date on the calendar after purchasing it so you’ll see it at the time you need to discard it.

When you’re using beauty products on your face, eyes, lips and skin, you want to make sure they’re fresh and sanitary. Pay careful attention to the expiry dates of beauty products!