As you prepare to bid adieu to 2010, it's also a good time to say goodbye to any makeup from 2009 or back that's still lingering in your cosmetics case. Sure, some products are just too pretty or special to part with, and those you may keep purely to covet. But the ones you actually use on your skin need to be regularly refreshed.
Here's the deal: Products past their prime often have a buildup of bacteria, and for eye makeup especially, this can lead to irritation or mild infection. Not to mention, old makeup simply doesn’t work as well—colors can oxidize and change, formulas can separate and look splotchy on your skin, and powders can dry out and cause a cakey finish. The general rule is to toss liquid or cream products that have been open longer than a year (unopened ones stored in a cool, dry place can last up to two years) or any makeup that suddenly has a change in texture, color, or odor. To help you determine whether it's time to replace your makeup, here's a guide to how long most products will remain fresh.
Mascara: Two to three months
It arguably gets the most use of any cosmetic, which explains why it conks out the fastest. If the formula suddenly starts flaking, clumping, or the wand doesn't glide through your lashes as easily as it once did, it's time for a new tube. You can also try the sniff test: Mascara develops a fuel-like odor when it starts to go bad.
Eye shadow and eyeliner: Three months
Products you use around your eyes need the most frequent replacing, because any bacteria they pick up can be transferred back to your peepers and cause redness, sties, and even pink eye. Cream shadows grow bacteria more quickly than powders, and the same goes for liquid and gel liners versus pencils (the constant sharpening of the latter helps remove bacteria).
Foundation and concealer: Six to twelve months
Any liquid product will begin to spoil within half-a-year to a year due to the water inside. The first clue that it's withering is when the color changes. Powder or stick formulas can stay good for up to two years, but again, any shifts in the color mean it's time to replace 'em.
Powder: Up to two years
Note I said "up to"—powders must be stored away from humidity (aka not in your bathroom), otherwise they'll start to absorb moisture and get clumpy.
Blush: Cream, a year; powder, up to two years
For both formulas, if the color has cracks, is harder to pick up on your finger or brush than before, or doesn't go on as vibrant as it once did, it's drying out and should be tossed.
Lipstick and gloss: A year
The color may still look pretty after this time period, but with repeated exposure to your mouth, it's a good idea to replace any lip product after 12 months. Some formulas may start to falter before then, though: Lipstick will feel hard and drag along you lips when you apply it; gloss will go on clumpy or streaky.
Makeup brushes: Several years if cleaned every two to three weeks
All of the above makeup will last longer if you regularly clean your makeup brushes and keep them far away from a steamy shower ('cause when your tools start to collect bacteria, so too will the makeup you dip them in). But once brushes start to fray or the bristles easily fall out, it’s time to invest in new ones.
Nail polish: There's no real expiration date for lacquer since it doesn't go on your skin, but when the formula separates—and remains so even after you shake the bottle—the shade is kicked.