I Scientifically Tested My Out-Of-Date Beauty Products And What I Found Wasn't Pretty

Using a science kit with Petri dishes and an agar solution, I used my makeup as an experiment to see just what lies within expired makeup.
Publish date:
April 23, 2015
health, makeup, beauty, makeup bags, Facial Products

For someone who is not a professional makeup artist, my cosmetics stash is like an episode of Hoarders: The Makeup Edition.

But my current swag is a mere sample in the ocean of full-size skincare, haircare, makeup and body products that washed up on my desk when I was a magazine beauty editor.

The daily beauty detritus was the envy of everyone at the magazine and I was on a first-name basis with all the couriers. However the amount I kept to review and write about was only a fraction of the beauty bounty I received, which made its way into the cosmetic bags of friends, family and colleagues, as well as being donated to charities and women’s shelters.

Still, who really needs five different black eyeliners or four bottles of self-tanner when you have olive skin?

As a beauty writer, I know the importance of adhering to the POA (Period After Opening) dates on the outside of the packaging on products that tell you when to ditch your items. But in reality? There are my hoarding tendencies (I blame my Mom -- she has makeup from the 1980s!) and a reluctance to throw out discontinued favorites and limited edition palettes. Cosmetics are expensive! I almost cried when I had to buy shampoo and conditioner again!

So I decided to use my makeup as an experiment to see just what lies within expired makeup and whether those shelf life dates are simply a suggestion.

Even though I know better, I’m terrible at cleaning makeup brushes and sanitizing my products. While I never share my personal care items, I’m a little lax when it comes to the recommended weekly washing of cosmetic implements (daily -- if you have acne-prone skin) and binning lippies past their prime. So I decided to do a little at-home experiment to see what nasties I was harboring in my makeup case.

I used a kids’ science kit with Petri dishes and an agar solution but you can also make your own bacterial culture medium. Once the agar had cooled and set in the deeper Petri dish, I used a sterile Q-Tip to swab three different types of my own used makeup, using a fourth Petri dish as a control.

I chose a three-year-old lipstick, a four-year-old lip gloss and four-year-old eyeliner to test. (Told you I was a hoarder!) While my home is a less than ideal controlled environment, a lid on each dish ensured no extraneous microbes would settle on the medium.

Finally, each dish was labeled and placed in a dark environment to do its thang. (Note: I live in a humid subtropical environment so heat and moisture are a constant and incubation is not a problem.).

I checked on my little cultures daily and removed my baby bacteria after five days to examine them closely. And -- it looked pretty gross.

The worst by far was the lip gloss sample, with plenty of angry dark eruptions, followed by the lipstick. Surprisingly, the eyeliner, which I expected would be teeming with bacterial colonies since it is used so close to the mucosa of the eye, had minimal discoloration and growths.

Next, I turned to the experts for their opinions on my experimental findings. Molecular biologist (and my baby bro) Dr Rudi Tannenberg identified the dark growths as mold and said some raised white markings could be bacteria, most likely Staphylococcus, which occurs naturally on our skin. Ewww.

Regardless of climate, he says mold spores are always in the air and when any item is exposed to air it is subject to mold contamination. While gross, mold is not generally dangerous. If you can’t see it on your products than it’s not in a high enough concentration to cause effects on your skin, according to my brother.

That’s not to be confused with oxidation that you might see occur on older powder-based cosmetics like eyeshadow, which is a reaction between the makeup pigment and oxygen in the air, causing discoloration and degradation of the product, giving it that crusty top layer and crumbly texture. Moisture can also degrade your makeup.

In the interests of thorough and not just familial research, I also checked in with pathologist Dr Renu Vohra, who specializes in bacteriology and molecular microbiology, and Emma Hobson, Education Manager for International Dermal Institute and Dermalogica.

Both experts agree that as soon as you open your cosmetic item, you contaminate it. According to Emma, it’s important to adhere to the PAO (Period After Opening) symbol guidelines on each product (usually between 6M to 36M, meaning six months or 36 months) so the item remains stable and the ingredients are still effective.

She also notes that water can contaminate open-topped products in the shower, and fingers in pots will also increase the risk of product contamination. Emma advises using products in packaging such as tubes, squeeze bottles and spritz toners, to minimize these types of contamination.

As one cosmetics spokesperson said to me: “You wouldn’t eat food that is out of date so why would you put products on your skin that’s out of date?” You can’t always see that your beauty buys are out of date if there are no obvious signs of mold or bacteria, but if your lippie smells a bit whiffy, your foundation has separated or your lip gloss has changed color, that’s a sign that it may be time to treat yourself to a new and uncontaminated product.

Using old products or unsanitized brushes can lead to skin irritations, infections and breakouts. And who needs that?

Clinique recommends replacing mascara every three months (your eyelashes harbor lots of bacterial organisms -- who knew?); foundation, blush and bronzer every 12 to 18 months; eyeshadows and eyeliners after three years; and hold onto lipstick and lip gloss for only two years.

Pay attention to the expiry date on your sunscreen (out-of-date sunscreen means no sun protection, people!) and skincare items to ensure the active ingredients in your lotions and potions remain effective.

If you want to extend the shelf life of your favorite products, you can try these beauty hacks. Scrape off the oxidized portion of your eyeshadow or blush. Sharpen your eyeliners and lip liners regularly. Don’t pump air into your mascara as it will dry out faster. Keep the plastic covers on your pressed powder to avoid bacteria transfer. And use the spatula that comes with your moisturizer instead of digging your fingers in.

Alternatively, Emma from Dermalogica recommends using a Q-Tip to extract products from jars and keeping your skincare and fragrance in a cool place away from direct sunlight. And while the recent story in Australia about a woman who contracted a life-threatening bacterial infection after using her friend’s makeup brush to cover a blemish has not been conclusively attributed to the use, it’s a timely reminder to never share your makeup, skincare or beauty products with anyone else, period!

As for me, my Petri dishes just solidify what I already preach but don’t practice. Time to update that moldy makeup case!