Onychophagia is a medical term used to describe the habit of nail biting. It is a common behavioral disorder that affects people of all ages, but it is most commonly observed in children and adolescents. This habit is often considered to be a form of self-grooming, although it can also be a manifestation of stress, anxiety, boredom, or other psychological or emotional issues.

The word “onychophagia” is derived from the Greek words “onycho,” which means “nail,” and “phagia,” which means “to eat.” It is a type of body-focused repetitive behavior (BFRB) that falls under the umbrella of obsessive-compulsive and related disorders. BFRBs are repetitive behaviors that cause harm to the body, and onychophagia is one of the most common forms of BFRBs, affecting up to 30% of the population.

Onychophagia, also known as nail biting, is a common behavioral condition characterized by the repetitive biting of one’s fingernails. Although it is a relatively benign habit, it can have negative impacts on both physical and psychological health


The main causes of onychophagia and provide a comprehensive explanation of each.

  1. Psychological Factors: Onychophagia is often associated with anxiety, stress, and boredom. People may resort to nail biting as a means of coping with negative emotions or as a way to relieve stress. Nail biting can also be a form of self-soothing, providing comfort and a sense of security in times of stress or anxiety.
  2. Habitual Behaviors: Onychophagia can also develop as a habit, starting in childhood and continuing into adulthood. People who engage in nail biting may not even be aware that they are doing it, and may find it difficult to stop without help.
  3. Childhood Trauma: Childhood trauma, such as abuse or neglect, can also contribute to the development of onychophagia. Children who have experienced trauma may resort to nail biting as a way to cope with their emotions and as a form of self-soothing.
  4. Family History: Onychophagia can also be hereditary. People who have family members with a history of nail biting may be more likely to develop the habit themselves.
  5. Mental Health Disorders: Onychophagia can also be a symptom of underlying mental health disorders such as obsessive-compulsive disorder (OCD), attention-deficit/hyperactivity disorder (ADHD), and body dysmorphic disorder (BDD). In these cases, nail biting may be one of several repetitive behaviors that individuals engage in as a way to relieve anxiety or as a compulsive ritual.
  6. Nutritional Deficiencies: Nutritional deficiencies, such as a lack of iron or vitamins B and D, can also contribute to onychophagia. People who have low levels of these nutrients may resort to nail biting as a means of satisfying their nutritional cravings.
  7. Environmental Factors: Environmental factors, such as a lack of stimulation or boredom, can also contribute to onychophagia. People who are in monotonous or dull environments may resort to nail biting as a way to pass the time or as a form of self-entertainment.
  8. Substance Abuse: Substance abuse, such as alcohol or drug use, can also contribute to onychophagia. People who abuse substances may engage in nail biting as a means of coping with the negative side effects of their substance use.


The following are the main symptoms of onychophagia:

  1. Excessive nail biting: The most obvious symptom of onychophagia is the act of biting one’s nails. This behavior may be done unconsciously and can be triggered by stress, boredom, or nervousness. The frequency of nail biting can vary from occasional to constant and may lead to the destruction of the nail and surrounding skin.
  2. Damaged nails: Nail biting can result in damaged nails that are misshapen, thin, or brittle. The nails may become infected and develop a fungal infection, which can cause pain and swelling. In severe cases, the nails may become so damaged that they are unable to grow back.
  3. Bleeding and pain: Nail biting can cause the skin around the nails to become irritated and raw. This can lead to bleeding and pain, especially if the person bites the nails down to the quick (the sensitive part of the nail).
  4. Chapped and dry lips: Nail biting can also cause the lips to become dry and chapped, especially if the person bites their nails excessively. This can result in discomfort and can lead to infection if not treated properly.
  5. Social stigma: People who bite their nails may experience shame and embarrassment about their habit. This can lead to social isolation and may have a negative impact on their self-esteem and confidence.
  6. Difficulty stopping: Despite the negative consequences of nail biting, people with onychophagia may find it difficult to stop the behavior. This can be due to a variety of factors, including stress, boredom, and habit.
  7. Nervousness and anxiety: Nail biting is often associated with nervousness and anxiety, and people who engage in this behavior may experience increased levels of stress and anxiety as a result. This can lead to a vicious cycle, where the nail biting behavior is used as a coping mechanism for stress, which then leads to increased levels of anxiety.
  8. Injured fingers: In addition to damaging the nails, nail biting can also result in injury to the fingers. This can include cuts, bruises, and infections.
  9. Oral health problems: Nail biting can also lead to oral health problems, including infection, inflammation, and damage to the teeth and gums.
  10. Psychological distress: People with onychophagia may experience psychological distress as a result of their habit. This can include feelings of shame, guilt, and anxiety. In some cases, the distress associated with nail biting may be so severe that it interferes with daily activities and relationships.


Here is a list of diagnostic tests that can help identify the causes of onychophagia:

  1. Physical Examination: A physical examination is usually the first step in diagnosing onychophagia. During this examination, the doctor will look for signs of damage to the nails and surrounding skin, such as broken skin, redness, and swelling. The doctor may also ask questions about the individual’s nail-biting behavior, such as how often they bite their nails and how long they have been doing so.
  2. Psychological Assessment: Onychophagia can sometimes be a symptom of an underlying psychological condition, such as anxiety, stress, or depression. To determine if there is a psychological component to the nail biting, a mental health professional may conduct a psychological assessment. This may include a clinical interview, behavioral observations, and standardized questionnaires to assess symptoms of anxiety and depression.
  3. Dermatological Evaluation: Nail biting can lead to various skin problems, such as infections, paronychia (an infection of the skin surrounding the nail), and fungal infections. To determine if there is a dermatological component to the nail biting, a dermatologist may conduct a dermatological evaluation. This may include a skin examination, laboratory tests, and culture tests to check for infections.
  4. Neurological Evaluation: Onychophagia can sometimes be a symptom of a neurological condition, such as Tourette syndrome or obsessive-compulsive disorder (OCD). To determine if there is a neurological component to the nail biting, a neurologist may conduct a neurological evaluation. This may include a physical examination, imaging tests, and laboratory tests to check for neurological abnormalities.
  5. Laboratory Tests: Laboratory tests can help determine if there is an underlying medical condition contributing to the nail biting. For example, a blood test may be conducted to check for nutrient deficiencies, such as iron-deficiency anemia, which can cause brittle nails and increase the urge to bite them.
  6. Allergy Testing: Allergic reactions to certain substances, such as nail polish, can cause itching and redness around the nails, leading to nail biting. To determine if an allergy is contributing to the nail biting, an allergist may conduct allergy testing, such as skin prick tests or blood tests.
  7. X-rays: X-rays can be used to determine if there are any underlying bone or joint problems causing the nail biting. For example, if a person has arthritis in their hands, it may cause pain and discomfort, leading to nail biting.

In conclusion, onychophagia is a common habit that can have various underlying causes, including psychological, dermatological, neurological, medical, and allergic conditions. To diagnose the underlying causes of onychophagia, a combination of physical examination, psychological assessment, dermatological evaluation, neurological evaluation, laboratory tests, allergy testing, and x-rays may be necessary.


The main treatments for onychophagia.

  1. Cognitive-behavioral therapy (CBT)

Cognitive-behavioral therapy (CBT) is a type of psychotherapy that aims to change negative thought patterns and behaviors. It has been found to be effective in treating onychophagia. The therapist works with the patient to identify the triggers that lead to nail biting and helps them develop coping strategies to avoid the habit. The therapist may also teach the patient relaxation techniques such as deep breathing and progressive muscle relaxation to help them manage stress and anxiety.

  1. Habit reversal training (HRT)

Habit reversal training (HRT) is a type of behavioral therapy that is specifically designed to help people overcome habits such as nail biting. HRT involves teaching the patient to recognize the urges and triggers that lead to nail biting and to engage in an alternative behavior when those triggers occur. For example, the patient may be encouraged to clench their fists or squeeze a stress ball instead of biting their nails. Over time, this alternative behavior becomes a new habit that replaces the nail biting habit.

  1. Nail biting deterrents

Nail biting deterrents are products that are designed to make biting the nails unpleasant or difficult. These products include bitter-tasting nail polishes, gloves, and bandages. The idea is that the unpleasant taste or sensation will discourage the person from biting their nails. While these products may be effective for some people, they may not work for everyone and may even lead to increased anxiety or stress in some cases.

  1. Medication

Medications such as selective serotonin reuptake inhibitors (SSRIs) may be prescribed to treat onychophagia in some cases. SSRIs are typically used to treat depression and anxiety, but they have also been found to be effective in reducing nail biting in some individuals. However, the use of medication should be closely monitored by a healthcare professional, as there may be potential side effects and interactions with other medications.

  1. Nail surgery

In severe cases of onychophagia, nail surgery may be necessary to repair damaged nails. This procedure involves removing the damaged portion of the nail and repairing it with skin grafts or other surgical techniques. Nail surgery is typically only recommended for individuals who have not been able to overcome their nail biting habit through other means.

  1. Hypnotherapy

Hypnotherapy is a type of therapy that uses hypnosis to help individuals overcome negative habits and behaviors. During a hypnotherapy session, the therapist induces a state of deep relaxation in the patient and then uses suggestion and visualization to help the patient overcome their nail biting habit. While there is limited research on the effectiveness of hypnotherapy for onychophagia, some individuals have reported success in overcoming their nail biting habit through this approach.

  1. Acupuncture

Acupuncture is a traditional Chinese medicine technique that involves the insertion of fine needles into specific points on the body. It has been found to be effective in treating a variety of physical and psychological conditions, including onychophagia. During an acupuncture session, the practitioner will place needles at specific points on the body that are believed to help regulate the flow of energy and reduce stress and anxiety.