Published in HealthWise September 2008

By Theresa Farrage

That tube of "perfect-for-my-skin-tone" foundation that's been in your makeup bag for two years could be ruining your perfect complexion.

That's because old, expired cosmetics are a perfect breeding ground for bacteria.

"The preservatives that prevent bacterial colonization do have an expiration period," said Dr. Mary Finnegan of Braddock Finnegan Dermatology in Omaha.  "When you repetitively use the products on areas of the skin, they may colonize the skin with harmful bacteria." 

So when should you throw away your cosmetics?

In dermatology, no strict rules exist regarding a makeup's shelf life because fome products have expiration dates while others don't, Finnegan said.

To be on the safe side, Finnegan offers the following tips on when to toss your old products and what can happen if you don't.

Eye Shadow and Eyeliner

Eye shadows come in cream or powder forms and both may harber bacteria.  Decrease the spread of bacteria by using a disposable applicator.  Some eye shadows contain nickel, cobalt, chromate and other metals that can cause an irritation or an allergic reaction.  Bacteria also can contaminate liquid and powder eyeliners, but these products usually have preservatives to lessen the risk of bacterial infection.  Like eye shadow, eyeliners can contain nickel or cobalt, which can cause an allergic reaction. Discard one year from the date the package is opened.

Foundation and Concealers

Many foundations and concealers contain sunscreen, which eventually expires.  It's vital to discard aged products.  Furthermore, if there's an odor, throw it away.  Discard one year from the date the package is opened.

Mascara

A mascara brush can serve as a vehicle for eye infections.  To decrase the risk of infection, don't share your mascara with anyone.  If the mascara brush becomes dry or if the mascara has developed an odor, throw it away.  In general, discard after using mascara for 1 1/2 to three months.

Lipstick and Lip Balm

Many lipsticks and lip balms contain sunscreens, making it even more important to consistently use a fresh tube.  The red dye in lipsticks can cause an allergic reaction in some women.  Discard after one year.

Makeup Brushes

Makeup brushes should be washed with soap and water weekly.  Brushes should be replaced periodically because they become less efficient with makup application over time and can harbor bacteria.

Facial Powders and Blushes

To reduce the potential for skin infections, discard after two years of use.

Facial Moisturizeers, Cleansers and Anti-Aging Products

Most facial moisturizers and cleansers have an expiration date printed on the packaging.  Since most of today's moisturizers contain sunscreens, discard one year from the date the package is opened.  Anti-aging products such as those containing retinol should be thrown away per the label's instructions as they may lose effectiveness over time.

Makeup Removers

Follow the instructions on the product's packaging.  Most makeup removers should remain effective for one year or longer.

Nail Polish

Discard about two years after opening the bottle.  Toss polish when the consistency changes (becomes runny or thickened).  Some people are sensitive to toluenesulfonamide (a nail resin) found in some polishes, or acetone, the active ingreedient in nail polish remover.

Ingredients Can Cause Skin Problems, Too

Makeup ingredients such as isopropyl myristate, coconut oil, squaliene, lanolin and mineral oil can lead to acene, said Dr. Mary Finnegan of Braddock Finnegan Dermatology in Omaha.

How you apply cosmetics and makeup also may lead to breakouts.  For example, vigorous facial massage may disrupt the acne-prone follicle, resulting in acne lesions.

In addition, many botanical ingredients in skin-card products have the potential to induce allergic contact dermatitis in some people, Finnegan said.

Costmetics also contain many potential allergens including PABA (para-aminobenzoic acid), fragrances, preservatives, proplyene glycol, lanolin, botanicals and vitamin E in those prone to develop contact allergy.  A dermatologist can do a patch test to try and identify the allergen.