You should always pay attention to how long you have had your makeup and get rid of it when it's past its prime! It can cause pimples and skin conditions! Below is a list of products and dates after opening of when it should be tossed away! (Bobbi Brown: Makeup Manual)

Liquid Foundation
Cream Foundation
Concealer
Powder
Mascara
Lipstick
Lip/Eye Pencils
Eye Shadow
Powder Blush
Cream Blush
Moisturizer
Eye Cream
Sunscreen
Face Bream

2 years
2 years
2 years
2 years
6 months
12-18 months
12-18 months
2 years
2 years
2 years
2 years

6 months
2 years
2 years