Nail biting (onychophagia): symptoms, cause and unlearning

You can stop nail biting in various ways. Nail biting is a common phenomenon in children aged 3, 4 and 5 years or older, but especially in teenagers. Nail biting occurs from the age of 3. It mainly occurs on the fingers, but sometimes also on the toenails. Most nail biters bite all ten nails equally. Nail biting is often embarrassing and socially undesirable. It leads to shortened and frayed nails. Nail biting increases the risk of infections on the fingers and in the mouth, because bacteria and dirt enter the mouth directly. Nail biting is therefore not only a dirty habit, but also an unhealthy habit with negative consequences. You can unlearn or stop nail biting in various ways. Several treatment measures can help you stop nail biting. Some focus on behavioral changes and some focus on physical barriers to nail biting. There are several effective ways to stop nail biting.

  • What is nail biting?
  • Who’s biting their nail?
  • Cause of nail biting: why do you bite your nails?
  • Stress and anxiety
  • Learned behaviour
  • Boredom
  • Perfectionism
  • What are the consequences of nail biting?
  • Nail disorders
  • Mouth and teeth
  • Mental health problems
  • Preventing nail biting in children and adults
  • How to unlearn and stop nail biting?
  • Rubbing nails with a bad taste
  • Learning different responses
  • Take care of hands and nails
  • Limit biting fingers
  • Plasters or artificial nails
  • Preventer against nail biting
  • Treatment for nail biters
  • Behavioral therapy
  • Medicines for nail biting
  • Prognosis


What is nail biting?

Nail biting or onychophagia is a common phenomenon in children and young adults, where the fingernails or toenails are bitten off. Children often stop biting their nails on their own as they get older. From the age of 18, the frequency of this behavior decreases, but it can persist into adulthood. It is mainly men who continue to bite their nails. Nail biting is a bothersome and socially undesirable problem that can occur on a continuum ranging from mild to severe. Nail biting involves repetitive and self-harming behavior. Nail biting can lead to paronychia, an acute inflammation of the cuticle.

Who’s biting their nail?

People of all ages bite their nails. About half of all children aged 10 to 18 bite their nails. Nail biting occurs most often during puberty. Some adolescents and young adults between the ages of 18 and 22 also bite their nails. Only a small number of adults bite their nails. Most people stop biting their nails before the age of 30. Boys bite their nails more often after the age of ten than girls. Nail biting can occur with other body-focused repetitive behaviors (BFRBs) such as skin picking skin picking disorder.

Cause of nail biting: why do you bite your nails?

Factors such as boredom, anxiety and stress are the most common causes of nail biting, even for toddlers.

Stress and anxiety

In some stressful situations, nail biting can reduce anxiety. Stress can cause nail biting to get distraction and a sense of relief.

Learned behaviour

Another explanation is that it is learned behavior; Nail biting often takes place unconsciously.


Nail biting can occur when a person is bored or lethargic and nail biting stimulates you and keeps you alert.


Nail biters can be provoked by the need to do everything perfectly. This causes stress, which can manifest itself in nail biting.

Nails of a nail-biting child / Source: Aboghetto, Wikimedia Commons (CC BY-SA-3.0)

What are the consequences of nail biting?

Nail biting is an annoying and unattractive habit that doesn’t look fresh and isn’t. This is because there is often dirt and grime under the nails.

Nail disorders

Nail biting can cause microtrauma to the cuticle, which can lead to cuticle inflammation. Important causative agents are skin bacteria such as staphylococci and streptococci. In severe cases, the infection can spread under the nail and affect the nail bed. Nail biting can also, in rare cases, cause deformities of the nails and fingertips. Prolonged nail biting can affect nail growth; it turns out that nail biting stimulates nail growth by about 20%.

Mouth and teeth

Nail biting increases the risk of oral infections because bacteria and dirt enter the mouth directly. Furthermore, excessive nail biting can cause dental problems due to the pressure on teeth and molars.

Mental health problems

Nail biting can sometimes also lead to psychological problems, due to the cosmetically disturbing effects and the negative social reactions it evokes. In the worst case, you end up in depression and social isolation. A vicious circle has then arisen of feeling bad and therefore biting your nails and then feeling bad again so you start biting your nails again, etc.

Preventing nail biting in children and adults

Nail biting occurs from the age of 3. It is estimated that 28-33% of children between the ages of 7 and 10 and approximately 45% of teenagers are nail biters.¹ After age 18, nail biting gradually decreases in frequency, but it may persist into adulthood. The prevalence of nail biting in people aged 60-69 years is somewhere between 4.5% and
10.7%.² Until the age of ten, it occurs equally in boys and girls. After that, it is 10% more common in boys.

Artificial nails / Source: Bvasilev1, Wikimedia Commons (CC BY-4.0)

How to unlearn and stop nail biting?

Stopping and unlearning nail biting can be done in various ways. What works well for one person may not work well for another. A combination of treatments and measures is preferable. The following measures are possible (often in combination):

Rubbing nails with a bad taste

Painting nails with a bitter-tasting substance.

Learning different responses

Learning competing responses, such as making a fist, squeezing a stress ball, etc. This is a fairly simple way to stop nail biting.

Take care of hands and nails

The care of hands and nails. Another measure is to care for hands and cuticles with cream, so that there are no hard skins or edges to nibble on.

Limit biting fingers

Limiting the number of ‘biting fingers’ to one or two can also help you stop biting your nails.

Plasters or artificial nails

Placing plasters on your fingers or using artificial nails (although some people also bite them) are measures that can be effective in stopping nail biting.

Preventer against nail biting

Using the Preventor. This relatively new aid is fitted and used by a dentist. It is a transparent bite plate, made of rubber-like material. After using the Preventor, nail biting is impossible. The Preventor is colorless and completely invisible to others and can be worn without any problems during work and private life. The preventor is worn for approximately four to six weeks, day and night. Because the vacuum sucks, the plate does not suddenly fall out of the mouth. The person can do almost anything with it, such as drinking, talking and kissing. The picture only needs to be turned off while eating. This is a very effective way to stop nail biting.

Treatment for nail biters

Behavioral therapy

There are many behavioral therapies to combat nail biting. Behavioral therapy, which focuses on changing the behavioral pattern, turned out to be the most effective method.³ This method focuses on relaxation, self-control through systematic registration, social support from the immediate environment and looking back on the difficult moments.

Medicines for nail biting

The antidepressant clomipramine can provide a solution for severe nail biting.


While some people outgrow nail biting, it can become a lifelong habit. Nail biting is usually a harmless cosmetic problem and you can avoid it with self-care measures. However, severe nail biting can lead to infection, dental problems and other problems that need to be treated.

  1. Leung AK, Robson WL Nailbiting. Clin Pediatr (Phila) 1990; 29:690–692.
  2. Gregory LH Stereotypic movement disorder and disorder of infantancy, childhood, or adolescence NOS. in: Kaplan HI, Sadock BJ, editors. Comprehensive textbook of psychiatry. 6th edition. Baltimore: Williams & Wilkins; 1995: p.2360–2362.
  3. Twohig MP, Woods DW, Marcks BA, Teng EJ, Evaluating the efficacy of habit reversal: comparison with a placebo control. J Clin Psychiatry. 2003 Jan;64(1):40-8.


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