Onychophagia Fast Facts

Onychophagia is a clinical term for chronic, uncontrollable nail biting.

People with the disorder may cause damage to their nails or fingers, and the behavior may also cause emotional distress or impairment.

Onychophagia is one of several body-focused repetitive behaviors (BFRBs), conditions in which a person engages in persistent body-related actions and is unable to stop.

BFRB disorder is considered related to obsessive-compulsive disorder (OCD) by some scientists.

United Brain Association

BFRB disorder is considered related to obsessive-compulsive disorder (OCD) by some scientists.

What is Onychophagia?

Onychophagia is a technical term that describes chronic, uncontrollable, and sometimes harmful nail-biting behavior. People with this disorder cannot resist the urge to bite their nails, and the behavior can cause damage to the nails, skin, or tissue surrounding the nails.

A related condition called onychotillomania involves picking at the nails rather than biting them.

Onychophagia is one of a group of mental health-related issues called body-focused repetitive behaviors (BFRBs). BFRBs are brain-related conditions in which a person compulsively engages in activities centered on their body. The impulses are recurrent and span an extended period. A person with BFRB may want to stop the nail-biting behaviors, but they cannot resist. In some cases, a person who exhibits nail-biting behavior may also engage in other BFRBs, such as hair-pulling or skin-picking.

When the behaviors and their consequences cause significant distress, impair the person’s ability to function socially, or cause physical harm, they may be diagnosed as a body-focused repetitive behavior disorder.

Symptoms of Onychophagia

Many people bite their nails, but their habit does not cause them harm or distress. Nail-biting rises to the level of a diagnosable disorder when it interferes with a person’s ability to function socially or emotionally. In some cases, the behaviors may cause physical harm over the long term.

Symptoms of the disorder can include:

  • Repeated nail biting, picking at the nails, or otherwise manipulating the nails
  • Feeling of tension in anticipation of the behavior (or when trying to resist)
  • Feeling of relief or pleasure after the behavior
  • Unsuccessfully trying to stop the behaviors
  • Distress at school, work, or home associated with the behaviors
  • Damage to nails or surrounding tissues
  • Damage to the teeth, mouth, or oral infections
  • Digestive problems

Variation of BFRB Symptoms

The severity of BFRB symptoms varies widely from case to case. Some people experience only mild symptoms, but others are significantly impaired by their behaviors. Some recognize that the behaviors are problematic, while others deny the problem’s existence.

BFRBs also vary in terms of the person’s awareness of their behaviors. For example, some people engage in the behavior without realizing that they’re doing it (automatic behavior). Others engage intentionally to relieve stress (focused behavior).

What Causes Onychophagia?

Doctors and researchers have not precisely determined what causes BFRB disorder, but they have identified several risk factors which increase an individual’s likelihood of developing the disorder.

  • Genetic Predisposition. Having a parent, sibling, or child diagnosed with BFRBs may increase the chance that you will also be diagnosed with the disorder. Researchers have made some progress in identifying the genes that may play a role in developing OCD-related disorders, but more research is necessary to determine the precise genetic connections.
  • Environmental Factors. BFRBs often seem to be triggered by stress. Childhood traumas may also be a risk factor for the development of the disorder.
  • Age. BFRB disorder usually develops in late childhood or early adolescence.

Women are more likely than men to seek treatment for BFRBs, but studies suggest the disorder is equally prevalent in boys and girls.

Is Onychophagia Hereditary?

Researchers have long suspected that biological factors rather than environmental factors primarily cause OCD, and some scientists believe that BFRBs are related to OCD. Studies of families where OCD occurs strongly suggest that a genetic component may be responsible. However, the connection between OCD and BFRBs is still a matter of debate, and some studies have called the association into question.

Studies of people with BFRB disorder suggest that those with a close relative who also has the disorder are at increased risk. However, most people with a family history of BFRB disorder do not develop the disorder.

How Is Onychophagia Detected?

Because the onset of onychophagia often occurs in childhood or adolescence, detecting the early signs of the disorder often falls on parents. Nail-biting most often begins after age 3 or 4, but it may develop in a child who has earlier engaged in persistent thumb-sucking.

In most cases, nail biting is not serious enough to cause significant problems. However, when BFRB disorder develops, the behaviors become so severe they interfere with a child’s functioning. However, the symptoms may be subtle at first.

Potential warning signs that onychophagia may have progressed to BFRB disorder include:

  • Avoidance of social situations
  • Trying to hide the areas of the body damaged by the behavior
  • Avoidance of close relationships
  • Poor performance at school
  • Use of alcohol or drugs

How Is Onychophagia Diagnosed?

To diagnose BFRB disorder, a doctor will first rule out other potential medical causes of the symptoms. If the symptoms seem to meet the diagnostic criteria for the disorder, the patient will likely be referred to a mental health professional for further assessment.

Diagnostic steps may include:

  • A physical exam. This exam aims to rule out physical conditions that could be causing the symptoms.
  • Blood tests. These tests will look at the patient’s blood chemistry for issues such as thyroid function. Screenings for drugs and alcohol may also be conducted to rule out symptoms possibly caused by substance abuse.
  • Psychological assessments. These assessments may take the form of questionnaires or talk sessions with a mental health professional to assess the patient’s mood, mental state, and mental health history. Family members or caregivers may also be asked to participate in these assessments.

The results of the psychological assessments will be compared to the diagnostic criteria for BFRB disorder in the Diagnostic and Statistical Manual of Mental Disorders. Comparing these criteria will help a mental health professional decide whether the symptoms indicate BFRB disorder or another psychiatric problem (such as obsessive-compulsive personality disorder, anxiety disorders, or depression).

The diagnostic criteria for BFRB disorder include:

  • Chronic behavior involving biting, swallowing, picking at, or manipulating nails, resulting in physical damage
  • Unsuccessful attempts to stop the behavior
  • Another mental or medical disorder doesn’t better explain the behavior
  • The behavior causes significant distress or impairment in social, occupational, or other daily functioning

How Is Onychophagia Treated?

Onychophagia usually doesn’t require treatment, and the behavior sometimes decreases or goes away as the person ages. In many cases, intervention strategies can reduce the behavior without the need for medical or psychiatric treatment. Common interventions include:

  • Keeping nails neatly trimmed or manicured
  • Application of bitter-tasting compounds to the nails. This approach is unlikely to be successful in severe cases.
  • Use of physical barriers such as gloves or mouthguards


Doctors do not often prescribe medication to treat nail biting. However, some medications have shown promise in treating other BFRBs, including hair-pulling and skin-picking, and those medications may be recommended by some doctors for some people with onychophagia. Several different medications may be used to treat and manage BFRBs, and individual medication plans depend on the patient’s age, responsiveness to treatments, and the severity of their symptoms.

  • Antidepressants. Selective serotonin reuptake inhibitors (SSRIs) may be prescribed to treat BFRB symptoms. Clomipramine, naltrexone, and olanzapine are also sometimes used.
  • Other Medications. The amino acid N-acetylcysteine may have some benefit for people with BFRB disorder.


The most commonly used therapeutic approach is cognitive behavioral therapy (CBT). This process focuses on helping the patient identify a pattern of harmful thoughts and construct strategies and solutions for dealing with them that don’t interfere with functionality.

Other types of therapy sometimes used to treat BFRB disorder include habit reversal training and acceptance and commitment therapy.

How Does Onychophagia Progress?

People with onychophagia often feel shame and embarrassment due to their compulsions, and their self-esteem generally suffers. Attempts to avoid embarrassing or humiliating situations can lead to social isolation, which may feed feelings of depression or anxiety. These negative feelings, in turn, may encourage more severe nail-biting.

Left untreated, onychophagia and other BFRB disorders may eventually lead to long-term mental and physical complications, including:

  • Fungal infections of the nails
  • Bacterial infections of the digestive system
  • Dental problems
  • Lack of close relationships
  • Emotional distress
  • Depression
  • Anxiety
  • School or work problems
  • Substance abuse

How Is Onychophagia Prevented?

BFRB disorders cannot be prevented, but early diagnosis and a consistent treatment plan can help manage symptoms and prevent them from becoming as disruptive as they would be if they were left untreated. Most people with a BFRB disorder need to manage it throughout their lifetime. In addition, faithful adherence to a treatment plan, especially if it’s working well, can help prevent a relapse into a state of severe symptoms. Therefore, it’s essential for those diagnosed with BFRB disorder to seek regular evaluation from their mental health providers and stick to any prescribed medication plan.

Onychophagia Caregiver Tips

Caregivers for someone with onychophagia or another BFRB disorder should consider these tips to help the sufferer and themselves cope with the disorder:

  • Learn as much as possible about the disorder.
  • Seek appropriate professional treatment for the sufferer.
  • Do everything possible to support the sufferer in the pursuit of treatment.
  • Find ways to have positive experiences with the sufferer that don’t focus on the disorder.
  • Find a support group for caregivers.

Many people with BFRB disorders also suffer from other brain and mental health-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with BSRB disorder:

Onychophagia Brain Science

Researchers are currently working on studies to find the source of BFRBs. Some studies have found differences in the brains of people with BFRBs compared to healthy brains. These differences include structural changes in the putamen, cerebellum, anterior cingulate cortex, and right inferior frontal gyri.

These diverse parts of the brain are responsible for varied functions, but a common thread among them is the control of movement. Some researchers believe that interaction between these brain areas regulates how susceptible we are to developing habitual behaviors and how good we are at suppressing habits when they’re inappropriate.

Some scientists also believe increased connectivity between the orbitofrontal cortex and the basal ganglia in people with BFRBs may play a role. They theorize that this hyperconnectivity may interfere with the brain’s reward-and-motivation system, which may explain why people with BFRBs feel satisfaction and relief when they engage in the behaviors.

Onychophagia Research

Title: Task Control Circuit Targets for Obsessive Compulsive Behaviors in Children

Stage: Recruiting

Principal investigator: Rachel Marsh, PhD

New York State Psychiatric Institute

New York, NY

This study will use magnetic resonance imaging (MRI) to assess the function and structure of overlapping task control circuits in children with a range of Obsessive-Compulsive symptoms (OCS). The functioning of task control circuits will be assessed using the well-validated Multisource interference task (MSIT). This study will also assess functional and anatomical connectivity within task control circuits in the same children, and determine whether disturbances in these overlapping circuits are associated with Obsessive-Compulsive Disorder (OCD) symptom severity. Behavioral measures will be administered to further assess regulatory, learning, and memory functions. Children with OCD will then be offered a standard course of up to 12 cognitive behavioral therapy (CBT) via remote video conference sessions or in-person visits when clinically indicated before scanning (along with age-and gender-matched control participants) to assess how these circuits may change with treatment. Children with subclinical OC symptoms will be offered a referral for treatment on an as-needed basis. In addition, de-identified data may be used in the future to conduct secondary data analyses. As more about OC symptoms and neurobiological mechanisms of interest in the current study are understood, data may be used to answer questions beyond those described in this protocol. All study procedures will be conducted on-site at Columbia University/the New York State Psychiatric Institute (New York, NY) and the University of Michigan’s outpatient Child and Adolescent Psychiatry (Ann Arbor, Michigan).


Title: Memantine in Body-Focused Repetitive Behaviors

Stage: Recruiting

Principal investigator: Jon E. Grant, MD, JD, MPH

University of Chicago

Chicago, IL

This study is eight weeks long and involves subjects taking memantine or a placebo. If they are randomly assigned to the memantine arm and are eligible to participate in the study, they will begin by taking 10mg once daily of memantine for two weeks, then 20mg for the remaining six weeks. Efficacy and safety measures will be performed at each visit. Participants will be randomized to receive either memantine or a placebo on a 1:1 basis. This blinding will be maintained by the IDS pharmacy at the University of Chicago.

The proposed study aims to evaluate the efficacy and safety of memantine in 80 subjects with DSM-5 trichotillomania (TTM) or skin picking disorder (SPD).

The hypothesis to be tested is that memantine will be more effective and well-tolerated in adults with trichotillomania or skin-picking disorder compared to a placebo. The proposed study will provide needed data on treating a disabling disorder where there are no current treatment options.

This will be one of the few studies assessing the use of pharmacotherapy to treat TTM and SPD in adults. Assessing the efficacy and safety of memantine will help inform clinicians about additional treatment options for adults suffering from this disorder.


Title: Theta Burst Stimulation Plus Habit Override Training for Compulsive Behaviors

Stage: Recruiting

Principal Investigator: Rebecca B Price, PhD

University of Pittsburgh

Pittsburgh, PA 

This project seeks to identify causal neural mechanisms underlying unwanted, repetitive behaviors (compulsions). Using non-invasive brain stimulation coupled with practice in a computer task, we will modulate activity in a target brain region and measure the effects on compulsive behaviors and related measures. This work could ultimately lead to the ability to treat compulsions more effectively by targeting the regions of the brain that can help or hinder attempts to overcome compulsions.

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