Nail biting or onychophagia involves damage to fingernails by means of habitual biting. Although not specifically indexed in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), nail biting is currently classified under Obsessive-Compulsive and Related Disorders in the DSM-5 and is considered to be a body-focused repetitive behavior.
Signs and Symptoms
Nail biting is often associated with visible nail damage, tension prior to or when attempting to resist nail biting, feelings of pleasure after biting, nail eating, and psychological distress. Many describe the behavior as “automatic.”
While few scientific studies have examined nail biting, it is believed to be a common behavior that typically begins in childhood. It is estimated that 20%-30% of the general population engages in chronic nail biting although prevalence estimates greatly vary, with estimates ranging from 12% to 44%. In addition to hair pulling disorder and skin picking disorder, frequently co-occurring behaviors include bruxism (teeth clenching or grinding), and cheek biting.