The make-up 'time bomb' include smelly and discoloured lipstick, mascara and eye pencils that can be a magnet for germs.Favourite beauty essentials - which also include foundation, concealer, blusher and perfume - all have a "period after opening" indicator denoted by an open pot with the number of months of safe use written inside.
Despite EU guidelines meaning brands have to state product shelf lives nine-in ten (89%) women are unaware such information exists, do not understand what the symbol means or are unable to read the often tiny writing. The result is almost seven-in-ten (68%) only replace make-up and skincare when they run out - however long that might take.
And nearly three-quarters (72%) never wash their make up sponges or brushes - even though they should do at least once a week. Eight in 10 (81%) also go to sleep at least once a week without removing make up, according to a survey of 1,000 women aged 18 to 70.
Sara Stern, director of cosmetics at Debenhams who carried out the study, said: "British women are famously loyal to make up brands and products, however, their reluctance to throw away old products is a risky business.
"We wouldn't hesitate to chuck out mouldy or bacteria-ridden food and the same standards should apply to the lotions and potions and that we put on our skin. Beauty is timeless but unfortunately, products are not."
Make-up, perfume and skincare products used after the expiry date carry a risk of irritation and infection because of infiltration by air and bacteria. Multiuse products carry an even higher risk as they can spread germs from eyes to skin to lips.
But six in 10 (60%) women admitted they shared make-up with friends and family - multiplying the chances of infection.
Bevis Man, of the British Skin Foundation, said: "It's not always obvious when make-up has passed its prime so it may not occur to people to replace their products.
"It is best to err on the side of caution and if a product looks or smells strange it is worth throwing it away.
"Cost is probably a major factor in why people do not replace out-of-date cosmetics. However, products can dry out and become less effective as they age.
"Your eyes are one area of your face you need to be particularly careful with, as eye infections can be painful and long-lasting.
"Make-up sponges are a particular haven for bacteria, especially if they are kept for a long period of time and are not washed. Again, it is best to keep them clean and replace them after a few months' use."
Debenhams is now exploring ways in which the 'best before' date of products can be better communicated to customers.
Staff members are being trained to point out the importance of regularly replacing products and a 'make up' amnesty is planned nationwide.
The retailer has also written to Health Secretary Andy Burnham to push for further legislation to cover the safety of consumers.
Ms Stern said: "Hopefully this call to action will encourage women to have a ruthless spring clean of their cosmetics collections.
"All our Beauty Hall staff members are on hand to advise customers of the use-by dates of their current items and help replenish any empty cosmetic bags."
Cosmetics have seen the highest growth in the British beauty market with a 7.4 per cent rise to £1,200 million between 2007 and 2008. They should be stored in a cool, dry place away from direct sunlight with the lid tightly closed.
Debenhams spokeswoman Ruth Attridge said eye shadow products can be kept for up to 15 years - more than 10 times longer than they should be.
She said: "Because you may not use it very often and it takes a long time to use up women, particularly elderly ones, have it lying around in their bags for an inceedible length of time - quite disgusting really.
"We asked women about the contents of their cosmetics bags and found it was out-of-date by an average of four years.
"The most dangerous products for health are those that go around your eyes because it is easy to pick up infections which are also easily transferrable when you share them with other people.
"Ignorance is a factor which is why we want to make the safety messages on packages much clearer.
"Expense is another issue so it could be an idea for manufacturers to make things like lipsticlks smaller so women are more likely to finish with them before the 'use by' date expires.
"Women don't like throwing things away without getting their money's worth but you have to remember it is probably no longer doing its job properly - and could well give you a nasty infection."