Anxiety and Stress
If you're a nail-biter, you're not alone. About 50 percent of kids and teens in the United States ages 10 to 18 bite their nails -- as do about 23 percent of adults ages 18 to 22. It's a hard habit to quit, but by age 30, most people have given it up [source: WebMD].
Nail-biting is a nervous habit, like fidgeting and thumb sucking, and people do it when they're stressed or bored. Mild nail-biting won't cause permanent damage, but it does leave your hands looking unkempt and bloody, and could also leave you susceptible to infection in your fingers and your mouth. To help quit, try stress-management methods and physical barriers such as bitter-tasting nail polish. Or, keep nails looking nice with frequent manicures -- tidy nails may deter you from gnawing.
Sometimes, though, nail-biting and picking is severe enough to be categorized by mental health professionals as an impulse-control disorder. It could indicate an anxiety or compulsive disorder and may require behavior therapy. If nail-biting is accompanied by hair pulling or self-mutilating behaviors, see a doctor.
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