AbstractBackgroundOnychophagia is a common disorder affecting 20% to 30% of the general population. It is defined as habitual nail biting and can cause various changes in the nail units. However, to date, there has been a paucity of data focusing on nail deformities related to onychophagia. This study was performed to investigate the clinical characteristics of onychophagia in Korea.MethodsThis study included 53 patients with onychophagia who visited the Pusan National University Hospital (Busan and Yangsan) over a 10‐year period (2011–2020). We retrospectively reviewed medical records and clinical and dermoscopic photographs.ResultsAll 10 fingernails were affected in 37.7% of the patients. The left thumbnail was the most predominantly affected site (81.1%). Clinical findings showed that short nails with ragged distal borders were the most common presentation (100.0%), followed by generalized or patchy rough areas (50.9%), linear and pinpoint hemorrhage (32.1%), longitudinal melanonychia (30.2%), transverse groove (28.3%), brittleness (28.3%), macrolunula (24.5%), washboard nail (13.2%), and pterygium (3.8%). Of the patients, 88.7% had periungual complications, such as periungual exfoliation (77.4%), absent or ragged cuticle (52.8%), hyponychial hyperkeratosis (37.7%), and paronychia (15.1%).ConclusionsAlthough onychophagia is a common disorder, its clinical characteristics have not been reported in the literature. The results of this study may be helpful in managing patients with onychophagia.