Nail biting: what are the dangers?

Onychophagia is characterised by thecompulsive urge to bite one’s nails. This can range from occasional benign behaviour to profound self-mutilation. In such cases, it becomes pathological, severe and uncontrollable onychophagia, a body-focused repetitive behaviour. This common habit affects both children and adults. Most instances of nail biting begin in early childhood, between 4 and 6 years of age, and tend to stabilise as the child grows, before intensifying during adolescence with the onset of puberty, or even persisting into adulthood. However, in many cases the behaviour usually diminishes with age: it ceases spontaneously and completely by the end of adolescence or in early adulthood. It can also emerge suddenly in adults, particularly following high workplace stress, a traumatic event (divorce, bereavement, etc.) or during withdrawal from substances (tobacco, alcohol, etc.). Studies have also shown 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 fully understood, but there may be multiple factors. They often begin 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 afterwards. It is viewed as a reflex of emotional imbalance : a reaction to stress, fear or overwhelming depression. Our emotional makeup (shyness, low self-esteem) also plays an integral part in why we resort to nail biting. Onychophagia also has a strong correlation with personality. Thus, some impatient or easily frustrated individuals frantically bite their nails to channel excess energy and regulate their emotions. This behaviour may also occur as an imitation of someone else, notably observed in children.

Biting one’s nails is one of the most common bad habits. Although we may not be aware of it and the action seems harmless, it can in reality give rise to 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.

Initially, the damage inflicted on the nails is minimal, but over time, as the habit becomes more entrenched, repeated trauma affects the nail bed and cuticle, and the damage becomes permanent. Chronic nail biting leads to irregular or ridged nail growth, altering the appearance of the hands. We can observe a deformation and weakening of the nail plate, as well as injuries and bleeding around the fingers. This can lead to feelings of shame and even social withdrawal, which intensifies stress and a range of other negative emotions, thereby perpetuating the habit.

Nail biting can also lead to the emergence of a hangnail, those small fragments of torn skin that hang at the edge of the nail and can become infected if not treated correctly. Individuals who bite their nails are often tempted to remove them entirely, which exposes more skin and thereby increases the risk of infection. Onychophagia can also induce the development of ingrown nails beneath the skin, which can be very painful. Although ingrown nails are much more common on the toes, nail biters should remain vigilant about the pain and infection risk associated with an ingrown nail. Should an ingrown nail occur, it is important to treat it promptly to prevent symptom aggravation and the onset of a serious infection.

Chronic nail-biting can also render you vulnerable to various infections (felon, paronychia). By biting your nails and cuticles, you create skin fissures around the nail margin through which 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, albeit rare, cases, the infection may spread to the underlying bone or the adjacent digit; removal of the infected nail may then be necessary to prevent further dissemination. Similarly, an individual who bites their nails and has oral herpes may develop herpetic whitlow on the bitten finger. Furthermore, once the infection has taken hold at the fingertip, it can propagate to other regions of the body.

Gingival dental problems.

Although it may not be obvious, the teeth are the first casualties of onychophagia. Biting one’s nails generates friction between the tooth and the nail which can gradually wear away the protective enamel at the edges of the incisors, or potentially even cause cracks or chipping. Furthermore, the constant pressure applied weakens tooth enamel over time, leading to increased dental sensitivity. This habit can also lead to loosening 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 exerted on the dental prosthesis.

Note: Individuals who have worn an orthodontic appliance or a retainer risk compromising the results achieved by biting their nails.

Biting one's nails also poses a threat to the gums. Nails serve as genuine breeding grounds for microorganisms, especially when infected (onychomycosis, paronychia), with debris that can build up under the nails from everyday contact. These microbes are then carried from the fingers to the oral cavity, potentially damaging or infecting the gingival tissues. Another risk linked to nail biting is bad breath, due to the constant introduction of germs into the mouth.

Biting your nails also increases the risk of developing chronic tooth grinding known as bruxism. This grinding can lead to additional orodental issues, including jaw pain and temporomandibular joint disorder. According to recent studies, nail-biting may cause jaw disorders. The forced position of the jaw during chewing can impair the temporomandibular joint and result in pain.

Gastrointestinal infections.

Harbouring microorganisms, nail biting can transmit a multitude of pathogenic agents capable of causing diseases (Eschericha coli, salmonella, cold-causing germs, etc.). Swallowing fragments of bitten nails can harbour pathogens responsible for various illnesses, ranging from the common cold to salmonellosis. We are therefore at risk of inflammation of the intestines, liver and stomach, which may present, for example, as diarrhoea or acute abdominal pain.

For these different reasons, it is therefore essential to take measures to progressively correct this habit.

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