For how many months - or years - have you been using that eyeliner, mascara or powder? Are you also guilty of using that smelly lipstick just because you love the shade?

You probably don't think about beauty products going bad like milk, but even nail polish has an expiration date, because cosmetics trap bacteria – and if you don’t put freshly opened lip-gloss directly on your lips when you go to Sephora, why would you use your own gloss after two years? Eww!

Using an old foundation could cause break-outs or irritation; lipsticks cause dry lips, swelling, itching and rashes, the use of old mascara can lead to bacterial infection in the eye; expired eye shadows leads to eye infections like red eye.

Some products mention a period after the opening date; to easily remember when you started using the product, just stick a reminder to it after calculating the date of expiry. If there is no expiry date mentioned on the product, you can calculate the expiry date from the date of manufacture mentioned on the product.

As a general rule, you should replace your mascara every three months, lipstick every one and a half years, eyeliner is 3 to 4 months, eye shadow every six to 12 months, for foundation, powder, and other facial makeup is 12 months. Perfume shelf life is 8 to 10 years, nail polish 1 to 2 years.

A very important point is to clean all your brushes at least once a week. Makeup artist Mario Dedivanovic, shared his tip to Into The Gloss: “To  clean my  brushes, I first wet them thoroughly with water and rub them gently onto a bar of antibacterial soap. I then rinse them with warm water and wash one more time with a gentle shampoo— Johnson's Baby Shampoo works well."

Makeup Brushes Clean the excess makeup, oil, dirt, and bacteria off of your contour, eyeshadow, and foundation brushes. Nicky J Sims/Getty

Now that you have all this information, is time to clean up your vanity. Remember is a new year, the perfect excuse to though away everything that doesn’t work and get new stuffs.