Nail biting, or onychophagia, is a common condition in which individuals habitually bite their nails and the surrounding areas. People may develop this behavior for a number of reasons, and it can lead to health problems. Treatment options and strategies, such as therapy, are available to help people stop biting their nails.

Onychophagia, or nail biting, describes a type of body-focused repetitive behavior (BFRB) that involves damage to the nails due to habitual biting. Some people may also refer to nail biting as a motor stereotypy. A BFRB describes a behavior that a person may perform to reduce stress. A motor stereotypy describes repetitive movements that do not seem to serve a purpose. These are common in children, but they can continue into adulthood.

Nail biting affects 20–30% of the general population. However, evidence suggests that it is more common in children and young adults, affecting about 37% of those aged 3–21 years. Possible complications of nail biting include gastrointestinal infections, skin infections, dental problems, and altered appearance of the nails.

As such, many people may try to manage this behavior. Some people may find that therapy helps them stop biting their nails. Others may prefer strategies such as trimming or covering the nails or applying bitter-tasting nail polishes.

In this article, we discuss the treatment options and management strategies for onychophagia.

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The American Academy of Dermatology Association (AAD) suggests the following tips to stop biting the nails:

  • Keeping the nails short: By regularly trimming their nails, a person can reduce the temptation to bite them.
  • Getting regular manicures: Similar to above, this may help reduce the urge to bite the nails. Spending money to keep the nails attractive may also serve as a deterrent.
  • Covering the nails: Covering the nails with tape or stickers may prevent biting. Alternatively, people can wear gloves.
  • Applying bitter nail polish: Applying a bitter, or foul-tasting, nail polish may discourage people from biting their nails.
  • Replacing the behavior: When a person feels the urge to bite their nails, they can try to keep their hands busy and away from their mouth by performing another activity, such as playing with a stress ball.
  • Identifying triggers: Although this can be difficult, a person may be able to notice triggers, such as boredom, stress, or anxiety, that cause them to initiate the behavior. Once they have identified any triggers, they can take steps to avoid them.
  • Trying to stop gradually: Taking a gradual approach, such as starting by not biting the thumbnails and then moving onto other nails, may be a successful strategy.

In addition to applying bitter nail polishes and practicing good nail hygiene, a 2021 paper suggests other strategies to help people treat and manage their onychophagia:

  • Applying olive oil: Putting olive oil on the nails may make the nails softer and less satisfying to bite. This may be a helpful method for younger children, who might find bitter nail polishes upsetting.
  • Cognitive behavioral therapy (CBT) with functional analysis: This form of CBT involves a trained professional observing the individual with onychophagia to help them discover any nail-biting triggers. The professional can then use CBT methods to help a person respond differently to those triggers.
  • Habit reversal therapy: This therapy involves a person building an awareness of their nail-biting behavior before trying to replace it with a different one, such as chewing gum.
  • Pharmacotherapy: In some cases, doctors may recommend the use of certain medications, such as selective serotonin reuptake inhibitors (SSRIs), to help with nail biting. However, doctors must make such prescriptions carefully, as SSRIs can worsen impulse-related conditions.

There is no single cause of nail biting, and researchers believe that many different factors could prompt someone to develop onychophagia. For example, there is evidence that onychophagia can be a response to a variety of stressors, such as school-related stress or family problems. Onychophagia may also indicate an underlying psychological disorder, such as anxiety.

There is also evidence to suggest that onychophagia may have a genetic component. For example, scientists believe that people with a family history of onychophagia are more likely to develop this behavior. Individuals whose biological parents both had onychophagia may be three or four times more likely to develop the condition themselves.

A common side effect of nail biting is visible damage to the nails and the surrounding areas. This damage may result in an unappealing cosmetic appearance, potentially causing feelings of shame, guilt, or embarrassment for some individuals. It can also increase the risk of other complications, including:

Other potential complications include alveolar destruction and intestinal parasitic infections.

Onychophagia is also associated with various psychiatric conditions, although it does not cause them. These conditions include:

Nail biting may also relate to other BFRBs, such as trichotillomania, which is hair pulling, or excoriation, which is skin picking.

Individuals who find themselves biting their nails frequently may wish to consider contacting a doctor. Similarly, if a parent or caregiver notices this behavior in a child, they may want to seek the advice of a medical professional.

Identifying and diagnosing this behavior can be difficult. A 2021 study notes that roughly 64% of doctors see nail biting in their practices but that almost 61% never or only on request ask about nail biting or examine the nails. This finding suggests that a person may need to bring onychophagia to their doctor’s attention.

However, a doctor can successfully diagnose this behavior after getting a detailed patient history and performing a physical examination of the hands. They can then suggest a multidisciplinary treatment approach.

Onychophagia is the clinical name for nail biting. It describes the impulsive and chronic behavior of damaging the nails through habitual biting. This condition can cause psychological issues, damage to the nails, and a variety of infections.

People can try implementing various treatments or strategies to prevent this behavior. The options include behavioral therapies, keeping the nails short, applying bitter-tasting nail polishes, and trying to identify potential triggers.