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Beauty hoarders beware: There just might be a horror movie-worthy amount of bacteria growing on your makeup, or says Jane Hollenberg, a 43-year makeup industry veteran, who has previously worked as a makeup chemist for Revlon, and now has her own laboratory.

I know what you’re thinking: Your makeup seems to be just fine no matter how long you’ve had it, right? Not quite. The reality is that you might just be smearing on a side of bacterial growth while applying your lipstick, mascara, and eyeshadow. And if that sounds dramatic, allow us to give you a guide to protect you from all those nasties.

“Nothing lasts forever, not food, not drugs, not cosmetics, not cloth, not paper, not wood, etc.,” says Hollenberg. “I am always surprised to learn how long people think cosmetics should last. Cooking oil becomes rancid, so will the oils used in cosmetics…”

Expiration Dates 101: How and Why

“In the United States, cosmetics are not required to have expiration dates,” says Hollenberg. “In Europe, cosmetics must show an indication of shelf life, usually PAO, meaning ‘period after opening’ during which the product remains functional.”

Just how do brands determine these ‘expired by’ dates?

Brands and labs put the product under what they consider to be normal and extreme situations to test the products longevity. “During product development, accelerated aging tests at elevated temperatures are used to predict shelf life, followed up by long term monitoring of product samples at ambient temperatures after a product is introduced to the market,” says Hollenberg. “A cosmetic never legally expires but can become non-functional. A product may spoil due to microbial growth. Most cosmetics contain preservatives to protect them against microbial growth, and tests are performed to evaluate efficacy of preservative systems. Evidence of microbial contamination could be an off odor or obvious mold growth. Water, or any product containing water is susceptible to microbial contamination.”

Makeup ‘Aging’

  • Your organic skincare will have to be tossed quicker than traditional formulas. “The popular natural ingredients have the shortest shelf lives. Natural oils become rancid more quickly than the synthetics that have been designed to be less prone to oxidation.”
  • Keep color of bottles and packaging in mind: “The color of some products packaged in clear glass or plastic may fade if exposed to light for prolonged periods.” This is especially true with oils, which are very light sensitive. It’s best if they are in dark bottles, like Jiva Apoha bottles always are, and stored away from light and heat.
  • If you love it, keep it sealed tight. “Most obviously, products containing water or other volatile material can dry out, quickly and severely, if the closure is not completely tightened after each use. Products begin to dry out more rapidly once they are partially used up, because any volatile can evaporate to some extent into the empty area in the bottle or jar.”

Below we’ve assembled a handy list of dates on how long makeup should last. Good way to track dates? Keep a notebook with all the dates you purchased (aka, it was exposed to air) your new favorite makeup buys. Or put a notice in your calendar. I know that seems extra, but your bacteria-free skin, eyes, and lips will thank you later.

When to Toss: Should They Stay or Should They Go

“Color, odor, or texture change are signs a product is aged,” says Hollenberg. “With the exception of water containing mascara and eyeliner, the suggested age limits are flexible. Just do not assume makeup lasts forever.”

Mascara: 3-6 Months

I know you splurged for that Diorshow mascara, and you love it and want to really get as much use out of it, but stay strict with this date. “Mascara is the most critical of any product, because it is used at the edge of the eye,” says Hollenberg. “With each use, the product applicator contacts the eye, then is inserted back into the product, thus contaminating it with microorganisms.”

And may seem obvious, but it must be said: “It is generally recommended that no one should ever share mascara or add any liquid or add water to a product to thin it out or use saliva to aid application,” reminds Hollenberg. And, of course, be diligent about shutting your mascara tight, and never pump it (You know when you see people push the wand up and down in the tube? Yeah, that.), never ever: It rushes in air, which leads to bacteria and dry out much quicker. And it honestly does nothing good for the mascara wand anyway.

And the same rules apply to eyeliners as well. Don’t take risks with your gorgeous eyes, it’s not worth getting infections or worse.

Foundation: 12-24 Months

But you still have a bit of your Charlotte Tilbury Light Wonder foundation, and you love it (I love it, too, and it never runs out.). Yep, but foundation needs to be tossed after a year or a year and a half or two years, depending on the formula.

If it’s in a jar, pot, or bottle, and contains water (it’ll say on the ingredient list), it should be tossed after a year because it has more exposure to air, brushes, and your fingers.

In a pump or airtight container? A year and a half.

Has SPF? Follow the expiration date on the back then.

Powder foundation? 24 months, unless an odor develops beforehand, then toss.

And always wash brushes weekly. Yep, weekly. Make it part of your weekly chores, like when you’re waiting for your clothes in the dryer, wash your brushes with a mild soap (I use organic dish soap), then lay them out to dry on paper towels (They won’t dry as quickly on towels and could develop mildew). And sponge applicators, aka BeautyBlenders, Hollenberg cautions those should be washed and dried fully after each use.

If it’s separated and looking a bit questionable (but still within the above timelines), it does not mean a foundation is unusable, as long as it can be shaken to remix the ingredients.

Same rules apply for blush. But those cream foundations, like Chantecaille Cheek Gelee, can be functional for at least 24 months.

Concealer: 12-24 Months

Concealer containing water should be thrown out within 12 months, or sooner if it’s in a vial with a foam applicator (like this type of applicator here).

Water-free cream concealer? You’ve got 24 months to run through that one.

But when applying concealer, especially if it’s from a pot (like my favorite NARS Soft Matte Complete Concealer), make sure hands are clean to assure bacteria contamination is lower.

Eyeshadow: 6-24 Months

Cream eyeshadow? “They usually contain oils that evaporate and will dry out within 6 to 12 months, depending on how they are packaged,” says Hollenberg. “Those in vials last the longest.”

Using a powdered eyeshadow? They should last about 24 months, minimum.

And as usual, your eyeshadow applicator brushes should be washed and dried weekly. And use best practices when applying eyeshadow too: wash hands before using your fingers in a cream eyeshadow.

Lips: 6-24 Months

Loving a classic lipsticks and lip gloss? They should remain okay for up to 24 months. But, of course, examine them to see if there is an off odor or appearance change, and discard if so. “Lipsticks are examples of wax/oil combinations that can develop an off odor due to rancidity,” warns Hollenberg.

Got a super long-lasting version (those ads that say they are kiss- and budge-proof)? Those have a shorter life shelf, they will usually dry up within 6 to 12 months.

SPF: Read the Label

“Cosmetics that are also drugs, such as those making sunscreen claims, must follow drug regulations, which do require an expiration date,” says Hollenberg. “You will see expiration dates on the packaging of a foundation or lipstick that claims an SPF.”

Read more about when to keep and when to toss other products:

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