How often do you wash your hairbrush? 

We wouldn't be surprised if you have to go quite far back in your memory to find the answer.

 Six months? A year? Never?

Well, you're not the only one.

Because let's face it, most of us just pull out a few hairs now and then before putting it back on the table.

But unfortunately for us, this is actually a pretty bad habit. In fact, we should be thoroughly cleaning our hairbrushes at least once a month.

And according to dermatologist Francesca Fusco, we should also be spray cleaning them once a week. Oops.

Francesca tells Allure: 'The less you shampoo, the more you use dry shampoo, the more you have dandruff, the more styling products you use, then the more frequently you should clean your brush.

'Residue, dead skin cells and oil colonise the brush and can become a home for bacteria and yeast which in general is not good and can smell unpleasant.'

Em… ew!

So seeing as a lot of us are total novices, Francesca tells us the most effective way of cleaning a hairbrush?

“The best way to clean it is to simply use a fine-toothed comb and rake it through the brush. It should easily catch all the hair and pull it free.”

“Then, run it under the sink and use your hands to massage the bristles to break up product that may be stuck in it. Then use your blowdryer and dry it up.”