Use nail hardeners sparingly

The take home message here is that a lot of them do more damage than good, says Stern. She reminds us that these products are not studied clinically, so most claims are not backed up by science. Unless nails are exceptionally weak and fragile, she says, most people don t benefit from a nail hardener. Healthy nails are flexible nails, she says, so to keep yours from breaking, avoid anything that makes them more brittle.