Change your foundation and concealer brush every 3 – 6 months, eye makeup brushes every 6 – 9 months if worn frequently, if not every two years. You should replace highlighter brushes every year, lipstick brushes every 3 – 4 months. Finally, you need to change your bronzer/blush brushes every 6 – 9 months if used a lot, if not every 1.5 – 2 years.
There are also other situations like fraying of makeup brush bristles. Fraying is ordinarily normal because most makeup brushes have synthetic fibers, but it is harder to get a natural finish with frayed makeup brushes. Similarly, if the brushes bristles shed, getting acne and breakouts are just another sign that you need to switch to a new makeup brush. The bristles of makeup brushes, made up of synthetic fibers, can also show discoloration and develop an unpleasant smell if not washed with care. If the discoloration and odor do not go away after a few washes, then it is time to replace them.