Children bite their nails for many reasons -- out of curiosity or boredom, to relieve stress, to pass the time, or from force of habit. Nail biting is the most common of the so-called "nervous habits," which include thumb sucking, nose picking, hair twisting or tugging, and tooth grinding. (None of these necessarily signals anxiety, so "nervous habits" is something of a misnomer.)
Nail biting is most common in high-strung children, tends to run in families, and is the most likely of the nervous habits to continue into adulthood. About one-third of primary school students and one-half of adolescents bite their nails, at least for a time; between one-quarter and one-third of college students say they still bite their nails.
If you know or suspect that a particular situation is making your child anxious -- a recent move, a break-up in the family, a new school -- make a special effort to help him talk about his feelings.
If your child's nail biting seems self-destructive, however, it's time to call his doctor or school counsellor. You should be concerned, for example, if his fingertips are ragged and bloody, or if in addition to biting his nails, he picks his skin, tugs on his eyelashes, or is not sleeping well. Also consult your child's doctor if the habit of nail biting surfaced suddenly and escalated quickly. You always want to check out the reasons behind a drastic change in your child's behaviour.
If, on the other hand, the habit doesn't seem to pose any physical or psychological threat, ignoring it is the best way to ensure that down the road your child will either stop on his own or ask you to help him quit.
If the habit bothers you, set limits. "No nail biting at the dinner table" is as reasonable a rule as "No feeding the dog from your plate." At other times, explain in a compassionate way that you know he can't help it, but you don't like to watch him biting his nails, so you're going to another room for a few minutes.
The most important thing is to keep what's basically a nuisance from escalating or getting laden with emotion. Stifling your anger for as long as you can and then snapping, "Stop biting your nails! I can't stand it!" is a recipe for disaster. If the situation is already tense, defuse it by being straightforward -- "I think we're both getting too worked up over this. I'm going to take a break from it for a while."
As long as he's not hurting himself and doesn't seem stressed out, your best bet is to wait out the habit. The less fuss he associates with his nail biting, the more likely he'll stop on his own when he's ready -- and the more likely he'll feel comfortable asking you for help.
If your child feels that reminders from you will help, choose a subtle signal -- a light touch on the arm or a code word. Encourage him to become more aware of when and where he bites, and identify some relaxation techniques he can learn -- deep breathing, or clenching and releasing his fists. You might attach a small pair of fingernail clippers to his key chain or belt loop, so he won't be tempted by snags. If he's old enough, teach him how to use an emery board and keep one on his bedside table or in a bathroom drawer.
Step three (and steps four and five and onward) are to try -- and try again. Explain to your child that different people respond to different techniques, and encourage him to be willing to try a variety of solutions if the first one doesn't work. In general, the older he is, the more responsibility he can take in this endeavour.
Children of all ages, like adults, may find a substitute habit useful (plasticine for car rides, a smooth stone to hold while reading or watching television). Let your child choose an activity. If he's under the age of 8 or 9, he might need help in making the switch: practice the alternative habit with him for a few minutes before school or at bedtime.
Calendars work well for children up to about age 9. Let your child select and place stickers on the days he doesn't bite his nails. For an older child, set up an incentive savings plan, in which he deposits #1 to start and then you put in #1 for every day he leaves his fingertips alone. Physical reminders work for some kids: your child may want to try keeping Band-Aids or stickers on his fingertips or painting his nails with a bite-averting solution such as Stop'n Grow. (Check any product's ingredients before trying it. Finally, remind him -- and yourself -- that habits are hard to break and that the two of you are on the same side. Take a break from habit-breaking if you need to. Eventually your patience and persistence will pay off.
There is a strong tradition here in Ireland that nail biting is associated with intestinal worm infestation, particularlyif the child has a tendency to like sweet and sugary things, as indeed virtually all children do. Research has shown that there is no evidence that nail biting has anything to do with worms.