OCD is most-commonly characterized by unreasonable thoughts and fears (obsessions) that lead you to do repetitive behaviors (compulsions). It's important to note that only certain types of nail biters--the extreme cases--fit into this category. "As with hair pulling and skin picking, nail biting isn't a disorder unless it is impairing, distressing, and meets a certain clinical level of severity," says Carol Mathews, M.D., a psychiatrist at the University of California, San Francisco. "That is not the vast majority of nail bitters," she says. "It is a very small minority of people."
What counts as clinical severity? "They have bitten so much that they are getting infections," Mathews says. "There is physical damage that is impairing their ability to use their hands."
Experts say that even non-OCD nail biting is unhealthy, as it can spread viruses and bacteria, lead to infections of the nail bed, and contribute to skin infections.
Image: Boy biting nails, via Shutterstock