My son is 11 years old and has a really bad habit of biting his nails. He has done this for a couple of years now. I have exhausted myself trying to get him to stop. His nails are so short that the finger sticks up far beyond the nail. Will his nails ever grow beyond his fingertips? Is this harmful to him?
Habits are hard to break, but as you already may have concluded, badgering is largely ineffective. His fingernails will grow back, and nail biting in and of itself, is not harmful. You may wish to consider why he bites his nails. Is he anxious? Are there specific situations that may be anxiety-producing in which he routinely bites his nails? For the usual anxieties that are part of life, some children may be able to substitute worry beads for nail biting.
For anxiety that seems excessive, consult your pediatrician about additional help that may be appropriate. In the meantime, use positive reinforcement (even small rewards) for those occasions when he is not biting his nails.