Dirty secrets – so what's lurking in your make-up bag?

Favourite beauty essentials such as foundation, concealer, blusher, eyeshadow, eyeliner, mascara, lipstick and perfume all include a "period after opening" indicator, denoted by an open pot with the number of months of safe use written inside.

Despite European Union guidelines meaning brands have to state product shelf lives, 89 per cent of women are unaware that such information exists, do not understand what the symbol means or are unable to read the often tiny writing.

Make-up, perfume and skincare products used after the expiry date carry a risk of irritation and infection. This is due to air and bacteria infiltrating the products. Multiuse products carry an even higher risk as they can spread germs from eyes to skin to lips – and 60 per cent of women admitted they shared make-up with friends and family, multiplying the chances of infection, while 68 per cent of women replace make-up and skincare only when they run out, however long that might take

and 72 per cent of women never wash their make-up sponges or brushes, even though they should do so at least once a week. Amazingly 81 per cent of British women also regularly (at least once a week) go to

sleep without removing make-up.

"It is best to err on the side of caution and if a product looks or smells strange, it is worth throwing it away," said Bevis Man of the British Skin Foundation. "Your eyes are one area of your face you need to be particularly careful with, as eye infections can be painful and long-lasting."

As a guide, here are some recommended use-by dates: mascara 4-6 months; highlighter, 6 months; concealer, 6-12 months; liquid foundation, 12 months; eyeshadow / blush,18-24 months; pressed / loose powder, 12 months; lipstick / lip gloss,12-24 months; perfume, 36 months.