Clear Signs It's Time to Toss Your Makeup and Skin Care Products

You should also get suspicious when your products start to smell different. Skin care serums and creams, lip glosses and mascaras are likely to "sour" in this way after they're expired.

"If you notice that your mascara starts to have a weird smell or a change in smell, toss it immediately," warns Natasha Moor, celebrity makeup artist and founder of her own cosmetics line. "Mascara is the cosmetics product that I recommend that you change most frequently to protect the health of your eyes. When you use it for too long, the brush can hold bacteria and dirt from your skin and potentially lead to an eye infection."

She suggests always washing your hands or using sanitizer before applying and reapplying your makeup throughout the day. This helps prevent it from becoming contaminated. And Moor's ideal "keep" time for mascara is a month, tops.

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