Mascara: 6 months
Prep + Prime Face: 6 months
Blot Powder Pressed: 24 months
These are found on many other beauty products like shampoos! Now, if I only knew what some of those other symbols meant! :)
So, what happens if a product doesn't have this symbol on the back? Many MAC products, such as lipsticks and eyeshadows don't have the symbol, and the best way to gage their expiration is Sight, Smell, Touch.
Sight: Does the product look mildewy, extra-runny, hard and/or shiny when it's not meant to be? Is the texture unusual?
Smell: Does it smell super waxy, rotten, or beefy (gross I know!)? Is it just foul smelling?
Touch: Is the product not applying the same? Is it abnormal in any way?
Answering these questions should tell you whether a product is still safe or not. To be honest, most products without the symbol either don't expire or last a long time, provided they're kept clean and sanitary. My first MAC lipstick was purchased in 2003, and guess what? Five years later, it is still totally fine- I will use it until it starts demonstrating expiree symptoms. I also have eyeshadows from the same time and they are in great condition. Generally, powder products that have not been exposed to oils and/or moisture never really expire. Keep your brushes dry and clean, and all your products in a non-humid spot, and you can rest a bit easier. But remember! Determining whether a product is safe to use is up to YOU. No one is responsible for the care of your products except you, so what may work for one person may not work for another, especially considering environment and other factors play a huge role in the care of cosmetics.
So, you may also have cosmetics with the symbol on them, but you think, what's the big deal if I keep them a little longer than they say? Maybe you don't use your foundation everyday, and by 24 months, it's still half full. Again, follow the Sight, Smell, Touch guidelines and if it's not showing any signs of decay, use at your own risk. Most of these products that have the jar symbol expiration are products that can easily get contaminated because they are liquid, they're exposed to oils (like face -> brush -> powder), or bacteria (mascara). Those guidelines are fairly generous and are there as a courtesy for your health and safety. Cosmetic companies are not legally required to have products/ingredients approved by the FDA, nor are they required to place an expiration date on products, but they do to keep us healthy. If it were me, I'd probably still use a product past its date (EXCEPT mascara! Not worth it!), but again, it's up to the individual to make that decision.
I hope this entry has helped you learn a little about what's fair game in your cabinet and what needs to be tossed! :)
For other great tips, check out Specktra.net's FAQ on the subject!