Biting Your Nails: What Are the Dangers?

Onychophagia is characterized by thecompulsive urge to bite one’s nails. This can range from occasional benign behavior to profound self-mutilation. In this case, it then becomes pathological onychophagia: severe and uncontrollable, that is, a body-focused repetitive behavior. This common habit affects both children and adults. The majority of nail-biting cases begin in early childhood, between ages 4 and 6, and stabilize as the child grows before intensifying during adolescence with the onset of puberty, sometimes even persisting into adulthood. However, in many instances, this behavior most often diminishes with age: it stops spontaneously and completely by late adolescence or in early adulthood. It may also emerge suddenly in adults, particularly after experiencing intense work-related stress, living through a traumatic event (divorce, bereavement, etc.), or during withdrawal (tobacco, alcohol, etc.). It has also been observed that boys are significantly more likely than girls to bite their nails.

The exact reason why some people bite their nails is not entirely clear or understood, but there may be several factors. The often begins as a coping mechanism in response to nervousness, boredom, loneliness, or hunger. It is also frequently associated with a psycho-emotional state of anxiety due to the self-soothing effect it provides afterward. It is seen as a reflex of emotional imbalances : a reaction to stress, fear, or excessive depression. Our emotional makeup (shyness, low self-esteem) is also an integral part of why we turn to nail biting. Onychophagia also has a strong correlation with personality. Thus, some impatient or easily frustrated individuals bite their nails frantically to channel their excess energy and regulate their emotions. This behavior can also occur as a means of imitation, notably observed in children.

Nail biting is one of the most common bad habits. And although we may be unaware of it and the act seems harmless, it can actually result in a number of negative health consequences affecting the entire body, both in the short and long term, beyond the effects it may have on the nails.

Physical damage to the nail and nail infections.

At first, the damage to the nails is minimal, but over time, as the habit becomes entrenched, repeated trauma affects the nail bed and cuticle, and the damage becomes permanent. Chronic nail biting results in irregular or ridged nail growth, which changes the appearance of the hands. We can observe a deformation and weakening of the nail plate, as well as injuries and bleeding on the fingers. This can cause shame and even social withdrawal, which intensifies stress and various negative emotions, ultimately reinforcing the persistence of the habit.

Biting one’s nails can also lead to the formation of hangnails, those small torn bits of skin that hang near the nail and can become infected if not properly treated. Individuals who bite their nails are often tempted to pull these loose skin fragments off, which exposes more skin and further increases the risk of infection. Onychophagia can also cause ingrown nails to develop under the skin, resulting in significant pain. Although ingrown nails occur much more frequently on the toes, nail biters should remain vigilant for the pain and infection risk associated with an ingrown nail. If an ingrown nail does develop, it is important to treat it promptly to prevent symptom worsening and serious infection.

Chronic nail biting can also make you vulnerable to various types of infection (felon, paronychia). By biting your nails and cuticles, you create skin fissures around the nail where bacteria, fungi, or viruses can infiltrate, leading to redness, pus accumulation, tenderness, and warmth in the infected area. Without treatment, onychomycosis can damage the nail. In the most severe cases, although rare, the infection can spread to the underlying bone or the fingernail; removal of the infected nail may then be necessary to prevent further spread. Similarly, someone who bites their nails and suffers from oral herpes can develop herpetic whitlow on the bitten finger. Moreover, once the infection has reached the fingertips, it can spread to other parts of the body.

Gingival dental problems.

Although it may not be obvious, the teeth are the primary victims of onychophagia. Biting one’s nails creates friction between the tooth and the nail that can gradually erode the protective enamel on the incisal edges, even potentially cause cracks or chips. Moreover, the constant pressure weakens the tooth enamel over time and results in increased dental sensitivity. This habit can also lead to gingival recession of the upper and lower incisors, creating gaps and misalignment between the upper and lower teeth (dental malocclusion) and causing dental crowding due to pressure on the prosthesis.

Note: Individuals who have worn orthodontic braces or a retainer risk compromising their results by biting their nails.

Nail biting also poses a threat to the gums. Fingernails are true breeding grounds for microorganisms, especially if they are infected (onychomycosis, paronychia), with debris that can accumulate under the nails from everything we touch daily. These microorganisms are then transferred from the fingers to the oral cavity, potentially damaging or infecting gingival tissues. Another risk associated with nail biting is the halitosis, due to the germs constantly introduced into the mouth.

Biting your nails also increases the risk of developing chronic teeth grinding known as bruxism. This grinding can lead to other dental and oral issues, including jaw pain and temporomandibular joint disorder According to recent studies, nail-biting can lead to jaw disorders. The forced position of the jaw during chewing can affect the temporomandibular joint and trigger pain.

Gastrointestinal infections.

Carrying microorganisms, nail biting can transmit a multitude of pathogens capable of causing diseases (Escherichia coli, Salmonella, cold‐causing germs, etc.). Swallowing chewed nail fragments can introduce pathogens responsible for various illnesses, ranging from the common cold to salmonellosis. Thus, we are at risk of inflammation of the intestines, liver, and stomach, which can manifest, for example, as diarrhea or acute abdominal pain.

For these various reasons, it is therefore crucial to take measures to gradually correct this habit.

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