How often do you clean your makeup brushes? Did you know makeup, bacteria and dead skin cells will build up in your brushes and can cause acne? If you already have a problem with acne, I recommend cleaning your brushes daily. Otherwise you are in a constant battle with acne causing bacteria and your skin will never get better. Just think about it, you are spreading bacteria around your face every time you use that dirty brush. If your skin is pretty good, you are probably okay to give them a good wash 2-3 times a week.