How long have you had that lipstick or eyeshadow? Be careful! Makeup Expires!

If you spend a lot on makeup, it's only natural to want to get your money's worth. But that doesn't mean you should hold onto your foundation and lipstick indefinitely. Old makeup can harbor bacteria, cause infections, and damage your skin, so it's important to know when to throw it away.

It's hard to tell when makeup is past its prime, since there's no expiration date on it.

The longer you use a product, the easier it is for bacteria to get into your makeup, potentially causing eye or skin infections. I recommend cleaning out your makeup bag every three months. Just like taking an inventory of your closet, it’s also important to regularly take inventory of your cosmetic products.

I like to give myself an hour or so to sit down and go through my makeup. It all depends on how much of a cosmetic junkie you are.

First, create a large space on a table so you have plenty of room. Get out all of your makeup and beauty products in your cabinets, under your sink, in your handbags, and so on. Next, separate your products into different piles such as foundations, lipsticks, blush, lip pencils, eye pencils, eye shadows, concealers, mascara.

Throw out anything that has a funny odor or looks discolored and get rid of any liquids that look separated.

Pitch eye shadows or pressed powders that look old or crusty around the edges, or those that have turned darker in color.

If you haven’t used an item in a year, get rid of it.

Old powder puffs or brushes that are falling apart and dingy makeup applicators and sponges all need to go.

If you're not sure how to tell when it's time to ditch old makeup, what are a few guidelines?

Foundation: One or two years after purchase, depending on whether it’s oil or water based. If it’s darker than when you purchased it or if it’s separating, throw it out.

Eye shadow: Two years or less; toss it as soon as you notice any discoloration or crustiness around the edges.

Blush: Two years or less; toss it as soon as you notice any discoloration or crustiness around the edges.

Eye and lip pencils: One to two years; typically, eyeliner and lip liner stops working when it’s past its prime.

Lipstick: One to two years; toss them if they start to feel dry or gummy.

Mascara: Three to four months tops! It’s not worth risking an eye infection.

Makeup sponges: Two to three days; they’re inexpensive to buy in bulk at a beauty-supply store.

Makeup brushes: Good-quality brushes will last many years if you clean them regularly and take proper care of them.

When you’re finished sorting and tossing, organize what’s left. Group together what you use on a daily basis, and put your special occasion or evening makeup in a separate drawer or bag.

Touch-up makeup should also go in its own bag so you can quickly grab what you need.

The best part is you’re aware of what you have, you won’t waste money buying more of the same stuff!