Applying your daily foundation, concealer, powders and eye shadows with the same make up brushes builds up products and oils on the brush. Over time, if the brushes are not washed frequently this can cause irritation to your skin and lead to breakouts. If you take the time to wash your face only to apply makeup with dirty brushes, you are returning unwanted oil and bacteria to your skin. So, how often should you be cleaning your brushes?

If you use your brushes on a daily basis,  you should be washing them at least once every two weeks but ideally once a week. This will remove bacteria, oil from your skin, germs and a build of makeup from the brushes.

“Lots of people don’t wash their brushes, but it’s probably one of the main contributors to break outs on our face. You should really be washing them with a gentle soap every week. Never go over a month without washing them because all sorts of things can start to build up and the longer they call your brushes home, the harder it is to get them out,” Margaret Venturella, a Pace student who interns for the beauty and grooming department at Nike said.

According to a board-certified dermatologist in New York City, Sejal Shah, M.D, in an interview with Women’s Health, the most common germs that contaminate makeup brushes after contacting your skin or makeup are Staphylococcus and Streptococcus, which are responsible for staph infections and strep throat.

“You can actually have a host of issues from dirty brushes,” said Shah in the interview. “Acne, skin irritation, rashes, bacterial skin infections, and eye infections just to name a few. I’ve even seen fungal infections and herpes.”

To clean your brushes, you should start by running the bristles under warm water. Point the brush bristles downward under the water to avoid getting water in the handle, it will loosen the glue that holds the bristles together.

Then, put a small amount of gentle soap into the palm of your hand. Baby soap or hand soap will work.

Take each brush and rub it around the soap in your hand until the brush has a good sudsy amount of soap on it. Massage the bristles with both hands to clean out the build up of makeup, do this for one to two minutes.

Thoroughly rinse the soap off the brush and lay them flat overnight to dry. Do not blow dry the bristles to speed up the process, the heat damages the bristles.

“It only takes about 10 minutes tops to clean your brushes and it’s definitely worth it for the sake of your skin. So take 10 minutes once a week and do yourself a favor,” Venturella said.