Onychophagia (Nail Biting)
Nail biting can be a temporary, relatively nondestructive behavior that is merely a cosmetic concern, but it can also develop into a severe, long-term problem. Onychophagia, or onychophagy, is considered a pathological oral habit and grooming disorder characterized by chronic, seemingly uncontrollable nail biting that is destructive to fingernails and surrounding tissue. Along with other body-focused repetitive behavior disorders (BFRBDs), onychophagia is classified in the DSM-5 as an “Other Specified Obsessive-Compulsive and Related Disorder.” Professional treatment, when necessary, focuses on both the physical and psychological factors involved in nail biting.
Onychophagia, which often results in visible damage to fingernails, may co-occur with other BFRBDs, such as hair pulling or skin picking. People who chronically bite their nails report distressful feelings of unease or tension prior to biting and feelings of relief or even pleasure after biting. In addition to tissue damage to fingers, nails and cuticles, nail biting can cause mouth injuries, dental problems, abscesses, and infections. The unattractive appearance of physical damage to skin and nails may cause feelings of shame, embarrassment and guilt, leading to complicated family and social relationships. Nail biting usually begins in early childhood, is most common during adolescence puberty, and may continue through adulthood, although the behavior often decreases or stops with age.
There may be a genetic link to onychophagia, since some people appear to have an inherited tendency toward developing BFRBs, as well as higher-than-average rates of mood and anxiety disorders in immediate family members. Nail biting is associated with anxiety because the act of chewing on nails reportedly relieves stress, tension, or boredom. People who habitually bite their nails do so when they feel, nervous, bored, lonely, or even hungry. Nail biting can also be a habit transferred from earlier thumb or finger sucking. While nail biting can occur without symptoms of a psychiatric condition, it can be associated with attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder, separation anxiety, enuresis, tic disorder, and other mental health issues.
Old-fashioned remedies specifically designed to prevent nail biting, such as applying bitter-tasting products to the nails, are generally ineffective. Barrier-type interventions that block contact between mouth and nails, such as gloves, mittens, socks and retainer-style or bite-plate devices can serve as impediments to biting or reminders not to bite. Treatment in severe cases must also focus on reducing or removing the emotional factors associated with nail biting. Cognitive behavioral therapy (CBT) with habit reversal training and progressive muscle relaxation and acceptance and commitment therapy (ACT) along with and a self-help technique known as movement decoupling has been shown to be beneficial in some cases of BFRBs. Any successful treatment of onychophagia requires the permission and cooperation of the child or adult who is biting their nails along with positive reinforcement and routine follow-ups.
The TLC Foundation for Body-Focused Repetitive Behaviors website. Nail Biting (Onychophagia)
Siddiqui JA, Qureshi SF, Marei WM, Mahfouz TA. Onychophagia (Nail Biting): A body focused repetitive behavior due to psychiatric co-morbidity. Journal of Mood Disorders. 2017;7(1):47-49.
Last reviewed 02/07/2019