Prevalence and correlates of onychophagia among Egyptian medical students: a cross-sectional study

Abstract

Background: Onychophagia, or chronic nail biting, is a common body-focused repetitive behaviour often associated with psychological stress, anxiety, and perfectionism. Medical students may be at increased risk due to sustained mental and emotional pressures. Objectives: To assess the prevalence of onychophagia, identify associated risk factors, and examine the relationship between perceived stress levels and the frequency or severity of nail biting among medical students at Tanta University in Egypt. Methods: A cross-sectional study was conducted among 330 undergraduate students using a structured self-administered questionnaire comprising sociodemographic data, onychophagia-related items, and the Perceived Stress Scale (PSS). Results: 57.3% of the students were actively practicing onychophagia, and it was reported more often among males (63.5%) than females (36.5%), but the difference was not statistically significant (p = 0.134). Among participants with onychophagia (n = 189), 18 (9.5%) were smokers, 63 (33.3%) reported a positive family history, and 30 (15.9%) reported fear of public spaces. These factors were significantly associated with nail-biting behaviour (p < 0.01 for all). No significant difference in Perceived Stress Scale scores was observed between students with and without onychophagia, and stress severity was not associated with the frequency or duration of nail-biting episodes. Conclusion: Onychophagia was common among medical students and was significantly associated with smoking, positive family history, and fear of public spaces. Behavioural interventions are recommended among university students.