Foundation and concealer
After you’ve opened the bottle, you can keep these around for 12 months-- max. When air hits a product, especially one that’s water-based, bacteria starts to form immediately. If the liquid starts to smell funny or separate before 12 months time, drop it in the trash.

Mascara and liquid liner
Every time you coat your lashes with the mascara wand or liner brush and dip it back into the product, you're spreading bacteria. Be strict with yourself about replacing these products every four months, even if they’re not empty or you risk an eye infection.

Pencil eye and lip liner
If you sharpen your pencils every two to three weeks, which is the best way of “cleaning” them, you can keep a pencil around for up to three years.

Pressed powder
Eye shadows, blushes, bronzers, and face powders can last up to two or three years if you keep them closed and dry. If you notice dark spots or bumps, it’s time to discard.

Lipstick
Lipstick with a wax-based formulation can last up to four years. A creamy lipstick can last two years at the most. If a lipstick is dry, crumbly, or has a dubious scent-- you know what to do.

Lip gloss
Gloss has a much shorter shelf life than lipstick-- one year. To extend the life of your glosses, use a makeup brush to apply them instead of your finger. You’ll add another year as you’re keeping the bacteria away.