The way a product is applied also determines the likelihood of it becoming a playground for bacteria. Pots and jars that require you to dip your fingers into the product are more likely to become contaminated than products that need an applicator.
If you're sick, use a cotton swab to apply eye and lip products, being careful not to double dip. Use a sponge when you apply foundation and toss it after each use. Also, avoid licking your lips before applying gloss to minimize the bacteria transfer.
Another consideration when deciding what to buy is that powders are a less welcoming environment for microorganisms than liquids and creams, Dr. Torres says.