First off, if your make smells or stinks, looks different or has separated you need to throw it out.
Make sure your hands are always clean before you start touching your make up. That's one way to decrease the amount of bacteria that gets on your make up.
All products have a different shelf life depending on what's in them.
Mascaras are the most notorious because they are breeding grounds for bacteria because of their wet and dark consistencies.
Oil-Free Foundation - 1 year
Concealer - 12-18 months
Powder - 2 years
Cream Blush - 12-18 months
Powder Eye Shadow - 2 years
Cream Eye Shadow - 12-18 months
Eyeliner - 2 years
Liquid Eyeliner - 3-6 months
Mascara - 3 months
Lipstick - 2 years
Lip gloss - 18-24 months
If you're using natural products, you will have to throw those out sooner because they do not contain any ingredients to help them last longer.
I've also noticed many make up companies including the number of months to keep the product once it's been opened.
If you cannot remember how long you've had it, it's a good indication that you need to replace it.
My next blog post will be about how to prolong the shelf life of your products by keeping them clean.