
Nail biting, or onychophagia, is closely related to mental disorders such as anxiety disorder and obsessive compulsive disorder. It is considered a pathological habit characterized by repetitive, seemingly uncontrolled nail biting behavior.
Along with other body-focused repetitive behavior, nail biting is classified in the DSM-IV under "Other Specified Obsessive-Compulsive and Related Disorder" and studies show that onychophagia is linked to several psychiatric disorders, including:
- Attention deficit hyperactivity disorder: Characterized by impulsiveness and hyperactivity, as well as difficulty paying attention.
- Oppositional defiant disorder: Characterized by defiance and disobedience toward people in positions of authority.
- Separation anxiety disorder: Characterized by excessive anxiety when separated from specific people or animals.
- Tourette syndrome: Characterized by involuntary movements and sounds.
Related behaviors include chronic skin picking, hair pulling, cheek biting, and teeth grinding.
What are symptoms of a nail biting disorder?
Onychophagia may cause symptoms such as:
- Feelings of tension before biting (which can manifest as anxiety, discomfort, excitement, etc.)
- Sensations such as itching, tingling, or pain that causes the person to bite
- Feelings of pleasure and relief after biting
- Feelings of guilt or shame about their nail biting
- Damage to the tissues around fingers and cuticles
- Injuries to the mouth or dental problems.
While nail biting is most common in children, onychophagia can occur in adolescents and even adults, who may develop the habit as a nervous tic.
According to a recent study, children with the nail biting disorder have lower affability, which leads to increased emotional problems, or (rarely) a neglected childhood.
What causes onychophagia?
While the exact cause of nail biting behavior is still a subject of scientific debate, studies have shown that nail biting may be caused by factors such as:
- Perfectionism
- Boredom
- Stress
- Loneliness
- Adolescence
Most researchers believe that people who engage in repetitive behaviors, such as nail-biting, tend to be perfectionistic. They may be unable to complete a task at an average pace, and when they do not achieve their objectives, they are prone to frustration, impatience, and dissatisfaction.
People who bite their nails typically begin this habit out of boredom or as a reaction to a stressful situation, but the behavior can become unconscious and start to affect them during routine activities such as watching television or reading.
Typically, nail biting develops during adolescence when the adolescent is experiencing new experiences and emotions. Scientists believe that most people eventually grow out of it.

SLIDESHOW
17 Everyday Ways to Ease Depression See SlideshowWhat are the treatment options for onychophagia?
Onychophagia can cause anxiety, emotional stress, and physical problems. Treatment depends on the severity of the condition. For example, mild onychophagia does not require treatment because children often outgrow the habit. Tips for preventing nail biting include:
- Avoiding overstimulation, which may be a trigger for nail biting.
- Occupying the mouth and hands (such as chewing gum)
- Managing stress and anxiety (such as through exercise)
- Keeping nails short, neatly trimmed, manicured, or covered to reduce the temptation to bite them
- Using bitter-tasting compounds on the nails to discourage nail biting (most doctors don’t recommend this tactic)
In some cases, behavior therapy may be required to address any underlying mental health issues or psychiatric disorders.
Pacan P, Grzesiak M, Reich A, Szepietowski JC. Onychophagia as a Spectrum of Obsessive-Compulsive Disorder. Acta Derm Venereol. 2009;89(3):278-80. https://www.medicaljournals.se/acta/content/html/10.2340/00015555-0646
Ghanizadeh A. Nail-biting; Etiology, Consequences and Management. Iran J Med Sci. 2011;36(2):73-79. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3556753/
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