The nail biting habit is hard to stop because it provides satisfying relief somehow. That can be a good thing; however, there are side effects that are not good. Some nail biters overdo it and often bite their fingernails until they bleed. This may open the way for germs to go directly in to the blood stream causing infection. Also some bacteria may enter the biter's mouth. These disadvantages may well be motivation enough to take drastic actions and stop the nail biting habit.
There are uncountable ways suggested on the Internet for breaking the habit of nail biting, as well as many other habits! Do a Google search. However, keep in mind there may be psychological factors worth looking into, such as being overly self critical, as suggested by Hand Analysis theory.
