The dangers of chronic nail biting include affecting nail growth and deformation. Nails belong to the connective tissue and are commonly used to protect the nail bed as well as to help the fingers do precision work, etc. If you bite your nails for a long time, it may affect the growth of your nails, and may easily damage the nail bed or nail plate, which may deform the nail plate or be infected by germs. In addition, biting nails for a long time may affect cause damage to the tissues around the nail, bleeding, etc., and may induce onychomycosis. If you cannot control yourself to bite nails for a long time, it may be a manifestation of obsessive-compulsive disorder, which is not conducive to human health. Long-term nail biting has more harmful effects, and patients are advised to improve their bad habits to avoid jeopardizing human health.