As Everyday Health reports, anything that you apply to your lips (lipstick, lip liner, even lip gloss) will last for about one year, potentially a little longer for lip-gloss, which can last up to two years. This is because lip products typically have a high water content, which makes them a breeding ground for bacteria and infection. Plus, you use these products on your lips every day, which means they are covered in germs. And always remember that if you recently had a cold sore you should toss that lipstick immediately.

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