As much as you love your limited-edition eyeshadow or favorite discontinued lipstick shade, the fact is that you can't hold on to your beauty products forever. Much like food, makeup has a “best before” date, especially once they have been opened. Not all beauty products are created alike and some may last longer than others. Here’s a guide on when it's okay to keep and when to toss your make-up:

MASCARA
Shelf Life: 2-3 months
Mascara is very prone to bacteria build up so don't make it worse by sharing yours with other people. You don't want to end up with a nasty infection so it's best to say no when a friend asks to borrow yours. In about 2 to 3 months, your mascara will start to dry up and get clumpy; this is your cue to toss it!

FOUNDATION
Shelf Life: 6 months-1 year
Foundation can start to get clumps in it, lighten in color and even change in smell when it's about to go off. If any of these signs show, it's time for your foundation to go!

LIPSTICK
Shelf Life: 2 years
The good news is that you can keep your beloved lipstick for up to two years before it needs to be chucked. But, if at any time it dries out, changes in color or emits a weird smell, then it's quite obvious that it needs to be replaced asap. For lip glosses, the shelf life is a little less at 1 year. Once it gets to sticky, toss!

EYESHADOW, PRESSED POWDER, BLUSH
Shelf Life: 2 years
To keep your powder products from going bad even before their expiration, make sure you clean your brushes thoroughly at least a couple times a week. Once these products become flaky or develop a film over them, it's time to buy new ones!

NAIL POLISH
Shelf Life: 1-2 years
When nail polish becomes dry and hard, starts separating into layers or becomes too thick to apply, then it's time to say goodbye, even if it's your favorite! You won't get the desired effect you want, anyway, so it's best to grab a new bottle.

Source: Erica Paredes, Hippie In High Heels