Many of us are guilty of trying to making our nail polish last as long as possible, says Choi. We hope to extend the life of our color with constant touch-ups, then when the chips become too noticeable to bear, we head straight to a salon for a fresh coat. This all makes sense for cosmetic purposes, but having nail polish on your nails for too long greatly damages their strength and overall health, warns Dr. Jaber. Even the safest nail polishes can leave your nails brittle, thin, and dry if left on for too long. Instead, fully remove your nail polish after five days and allow them the same amount of time to recover before getting them re-painted.