Business Insider (1/4, Russo) stated that although nail biting is a common habit affecting about “20-30% of people,” it’s also an unhealthy one that “increases the chances of teeth cracking, chipping, or wearing down.” The article reported that the habit may also damage nails and increase the risk of infections and illnesses. To stop biting nails, the article recommended keeping “nails trimmed and applying a preventative polish.”