Most in-use make-up products such as beauty blenders, mascara and lip gloss might be contaminated with potentially life-threatening superbugs, including E. coli and Staphylococci, according to a study.
Bacteria that can cause illnesses ranging from skin infections to blood poisoning if used near eyes, mouth or cuts or grazes were found in nine out of ten of the products, said the researchers from Aston University in the UK.
The study, published in the Journal of Applied Microbiology, shows that make-up products are contaminated with potentially fatal bacteria since they are often not cleaned and are used far beyond their expiry dates.
This risk is amplified in people with a weak immune system, who are more likely to contract infections from opportunistic bacteria, they said.
"Consumers' poor hygiene practices when it comes to using make-up, especially beauty blenders, is very worrying when you consider that we found bacteria such as E.coli -- which is linked with faecal contamination -- breeding on the products we tested," said Amreen Bashir, who co-led the study.
"More needs to be done to help educate consumers and the make-up industry as a whole about the need to wash beauty blenders regularly and dry them thoroughly, as well as the risks of using make-up beyond its expiry date," Bashir said in a statement.
The relatively new beauty blenders - sponges used to apply skin foundation products - were found to have the highest levels of potentially harmful bacteria, with the vast majority (93 percent) not having ever been cleaned the researchers said.
This was despite more than two thirds (64 percent) of beauty blenders being dropped on the floor at some point during use, they said.
The study is the first to look at beauty blender products, which are hugely popular make-up sponges used to blend foundation and contouring on the face, the researchers said.
Often endorsed by celebrities, these sponges are estimated to have sold over 6.5 million worldwide, according to the researchers.
They found these products are particularly susceptible to contamination as they are often left damp after use, which creates an ideal breeding ground for harmful bacteria.
The findings reveal that consumers are unwittingly putting themselves at risk, and that manufacturers and regulatory bodies should do more to protect their customers by making expiry dates and cleaning requirements more prominent on packaging, the researchers noted.