NEW YORK (CBSNewYork) — Lipstick, mascara, foundation – these are just some of the beauty items gals like to use on a daily basis.

But how long do you hold on to them? Keep them for too long and you might end up with some serious problems. Did you know you should replace mascara every four months?

More: The 5 Best Summer Beauty Products For New Yorkers

Lifestyle expert Sarah Bernard visited The Couch to tell us why the shelf life of our makeup is so important for the health of our skin. Check out the video below for her advice, and tips on how to use makeup properly.