How to Stop Biting Your Fingernails. Nail biting is a common habit and one that's not easy to kick. For some, this habit occurs when nervous or possibly when bored. However, following these steps may help you manage it and possibly quit altogether.
Purchase a bitter-tasting formula made expressly to stop nail biting. Choose the worst-tasting solution you can find.
Wash hands every morning with soap and water and towel dry.
Apply a liberal amount of the solution to the nails, cuticles and surrounding skin.
Continue to reapply the solution throughout the day as it wears off.
Reapply the solution at bedtime. Make sure the bitter taste is always present on your nails.