Onychophagia is associated with impairment of quality of life.

Onychophagia is defined as a chronic nail biting behaviour affecting about 20-30% of the general population. However, nail biting seems to be an ignored problem in a daily clinical practice. We have analysed the influence of onychophagia on quality of life (QoL) and stigmatisation level among 339 medical students with and without nail biting. Those with onychophagia demonstrated significantly higher QoL impairment compared to the controls (p < 0.001). Subjects who had been unable to stop nail biting behaviour in the past (p < 0.01) had visible nail abnormalities (p = 0.03), spent more time on nail biting (p = 0.02) and with a higher number of involved fingernails (p = 0.03), demonstrated further impaired QoL. Furthermore, tension before or when trying to resist nail biting (β = 12.5; p < 0.001), suffering due to nail biting (β  =12.6; p = 0.001) and nail eating behaviour (β = -7.5; p < 0.01) were independent variables influencing QoL. Participants with onychophagia also demonstrated higher level of stigmatisation (0.6 ± 1.2 vs. 0.2 ± 0.6 points, p < 0.01), although in both groups the stigmatisation level was low.