We know how much you love that perfect pink lipstick.

Or theeyelinerthat’s been sharpened down to no more than a nub.

So how do you know if your makeup has expired?

woman applying yellow eye shadow and holding a compact mirror

Getty Images

Much of what makes or breaks the longevity of a makeup product boils down to preservatives.

So what’s your first course of action?

Check for an expiration date on the label some, though not many, products include this.

period after opening pao symbols

Getty Images

More, however, feature a symbol that reflects the PAO or period after opening.

If your eyes are still irritated a day or two later, see an eye doctor.

Foundation

With the exception ofpowder formulas, foundations are water-based, which means bacteria love them.

“Separation can make the preservative system less effective and therefore make the product prone to contamination.”

Face Powder

Powders, both pressed and loose, are the Energizer Bunny of makeup.

They keep going… and going for up to two years.

With powders or creams, texture is also an indicator that it’s time to toss.

Eye Shadow

Eye-enhancing shadows?

Pay extra attention tocream-based shadows, which tend to grow bacteria more quickly than powders.

Eyeliner

Liquid or pencil, these eye definers should be replaced about every three months.

Shake it, and if the formula remains separated, it’s done-zo.

Disposable makeup sponges should be replaced after two uses one side, then the other.