And that, say experts, can affect your skin by causing irritation and even infection. Why? Because past-it makeup is a breeding ground for nasty bacteria.
The minute you open a makeup or skincare product for the first time it starts to be contaminated with bacteria from the air and from your fingertips. Once they have deteriorated, they don't work properly, plus the breakdown of ingredients such as fatty acids can produce substances that irritate your skin.
The survey suggests women keep lipsticks and lip glosses for up to ten years, rather than the one to two years recommended on the labels. And eye shadows and powder blushes aren't thrown away for a whopping 15 years, whereas the recommended pot life is anything up to two years.
To spring-clean your makeup bag, bin anything that's past its 'best before use' date (find the logo on the label that looks like an opened jar). If something looks or smells off, throw it away, along with sponges that haven't been washed regularly.
What's the oldest item in your makeup bag?