Brushes tend to collect oil, dust, dead skin and bacteria. Once you spread more product with a dirty brush, you're increasing your chances of clogging your pores and causing a break out.
Irritated skin 2
A dirty brush can transfer a bunch of grit onto your face, which could cause red irritated patches to form--especially if you have sensitive skin.
Styes are pretty nasty pimples that develop on the eyelid and are difficult to get rid of. Using dirty eye-shadow brushes on your sensitive eye area could cause these pesky styes from forming.
Staph infection 5
If you have any broken or punctured skin, it increases your chances of getting a staph infection when using dirty makeup brushes. Severe fungal infections like these can be avoided with a simple cleaning.
Pink eye 6
Pink eye is another infection that could be caused by using dirty eye shadow brushes or a mascara wand that is way pass its expiration date. You should change your mascara every 3 to 4 months.
Thinning brows 7
Using a dirty eyebrow brush will force heavy oils unto the hairs, which will eventually break off once you comb through. Make sure you rinse the brush and air dry.
Cold sore 8
A dirty lip brush could cause nasty cold sores--especially if you share your products with other friends or family in your household.
Fallen eyelashes 9
If your eyelash curler has accumulated sticky mascara, it will be easier for your natural and healthy lashes to fall out.