Biting your nails is unsanitary and can damage the skin around the nail increase the risk of infection, and harm teeth. To stop nail biting, the Mayo Clinic recommends the following: avoid factors that trigger nail biting; take steps to manage stress and anxiety; keep your nails neatly trimmed; occupy your hands or mouth, such as by chewing gum; and apply a bitter-tasting lacquer to nails. If you’re concerned about nail biting, consider talking to a doctor or a mental health professional.

Mayo Clinic, June 2019