People should be changing and washing their towels more often for several reasons.
Microbiologist Dr Orla Cahill was responding to a survey, which found men are more likely than women to clean their towels just once a year.
The survey by UK bathroom supplier Showers to You found 3% of respondents wash their bathroom towels once a year.
Almost one-in-10 of those surveyed only washed their bathroom towels twice a year, while one-third said they washed their bathroom towels just once every three months.
The study found men were five-times more likely to clean their bathroom towels once a year, with 5% of male respondents admitting to giving them an annual wash, compared to 1% of women.
Dr Orla Cahill, Microbiologist at TU Dublin, told The Hard Shoulder a towel shouldn't be used for more than three days.
"I was quite shocked by this survey to be perfectly honest," she said.
"Let me say my skin kind of crawled when I heard about it.
"The rule of thumb would be every two to three days minimum.
"It's not really that hygenic to keep a towel longer than two to three days".
She said this is because of accumulations of "sweat, dead skin cells and also skin bacteria."
Bath towels on a rack, 14-2-11. Image:Peter Scholey / AlamyDr Cahill said there is some room for manoeuvre.
"Theoretically it all depends on your level of activity, how much you perspire and how often you do shower," she said.
"In general two to three days you should change your towels - especially a bath or a shower towel.
"With a face towel that would be once a day".
Dr Cahill said your face is more sensitive than other areas.
"It can lead to skin breakouts because of skin bacteria like staphylococcus aureus or staphylococcus epidermidis - acne breakouts on your skin, rosacea maybe - as a result of a dirty towel".
Dr Cahill said dust mites are drawn to dead skin cells, while bacteria can multiply "especially if you put a damp towel on your radiator."
"I would typically air dry it, so allow it to air dry not in direct heat".
Dr Cahill said people also shouldn't be using the same towel on their face and body.
