“Brushes need to be cleaned at least monthly," says dermatologist Joel Schlessinger, MD, founder of LovelySkin.com. "If they aren't, they become dirty and full of bacteria from constantly touching our skin.”
He recommends utilizing a disposable brush system such as Klix, so you don’t have to worry about regular cleaning. But if you've invested in professional makeup brushes, cleaning them once a week is the best way to keep them soft and make them last longer.
Here's how to clean your brushes: Wet the hairs under the faucet with tepid to warm water. Use a mild shampoo (baby shampoo works great) or liquid hand soap and gently press it through the hairs with your fingers, adding a little water as you go. Rinse and repeat until the water runs clear. Make sure the hairs are pointing down the entire time.
After your brushes are clean, rub them a little on a clean paper towel and lay them to dry on their side. Never leave them to dry with the brush hairs up or in a brush holder. The water can run down in to the ferrule and loosen the glue holding the brush together over time.