The packaging for Latisse says that you need to use a separate brush for each eye and dispose of them after each use. In all actuality, you can use the brushes again and again. Most of my staff members switch brushes weekly or so; one even uses one brush the entire time. There's no dispensing of "additional" brushes by Allergan, so really, just use the same brush for a few days and then toss it. You can rinse them off if you'd like in between uses.