LONDON (Reuters Life!) - The average British woman's cosmetic bag is out of date by a worrying four years, according to a study on Wednesday 24 February.

Women are using cosmetics well past the use-by date, unaware that some products could be magnets for germs which could damage their health and looks, said Sara Stern, Director of Cosmetics at retail chain Debenhams.

"British women are famously loyal to make-up brands and products, however, their reluctance to throw away old products is a risky business," Stern said in a statement.

"We wouldn't hesitate to chuck out moldy 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."

Favorite 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.

Debenhams asked 1,000 women aged 18 to 70 about the contents of their cosmetic bags and their understanding of the health considerations.

Despite European Union guidelines meaning brands have to state product shelf lives, 89 percent of respondents said they were unaware that such information exists, did not understand what the symbol meant or were 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, Debenhams said. 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.

To add to the shock factor, 60 percent of respondents admitted they shared make-up with friends and family, multiplying the chances of infection.

More than two thirds of women (68 percent) said they only replace make-up and skincare when they run out, however long that might take.

Nearly three-quarters of those surveyed (72 percent) never wash their make-up sponges or brushes, even though they should do so at least once a week and 81 percent of British women also regularly (at least once a week) go to sleep without removing make-up.

Bevis Man of the British Skin Foundation said it was not always obvious when make-up had 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."

(Reporting by Paul Casciato, editing by Steve Addison)