If you absolutely hate being wasteful, then you probably thought at least once or twice about your grooming products’ expiration dates and whether they are real or a con. You’ve probably never abided by or even noticed the “best used by” symbol anyway so perhaps you’ve been using products that have expired and putting those on your face. Well, we wouldn’t want that to happen.

Though you may hate it, it actually does feel good to throw things out. Most of us have held on and used old grooming and makeup products, and kept them laying around for years on end without having the heart to get rid of them.

You may have never noticed this, but every product comes with a “Period After Opening” (PAO) symbol. As it turns out, the symbol is a type of expiration date. For example, if the symbol says “18M” that means the product is definitely going to be safe and functional for 18 months after opening. This counts as the PAO of the product. Some products say “6M” while others may say 2Y. This varies from brand to brand and product to product.

Most products are required to have the symbol so they either have the printed expiration date on them or are inherently guaranteed to remain good to use within a year following purchase. With aftershave, shampoo, and conditioner, you don’t really need to care about the expiration date. It can be more flexible because some cosmetic products tend to have greater stability and don’t have active ingredients that could potentially go bad.

If a product has a PAO symbol, that means you should toss it after its expiration date. It’s probably okay if you use it for a month or two after the recommended vendor date, but for example, skincare items will not be good to use after their PAO timeframe because they become bacterial bombs.

PAO symbols and expiration dates are basically a liability insurance for the companies manufacturing these products. Learning the PAO symbol is a great way to know when you can actually throw products instead of holding onto them.