Typically it begins in childhood, continues through adulthood, and the consequences are not limited to exposed fingertips, say dermatologists from the American Academy of Dermatology who want to help you let them grow.
"Chronic nail biting can cause serious problems," says board-certified dermatologist Margaret E. Parsons, MD, FAAD of the University of California, Davis. "In addition to making the skin around your nails feel sore, repeated nail biting can damage the tissue that makes nails grow, resulting in abnormal-looking nails. It can also leave you vulnerable to infection as you pass harmful bacteria and viruses from your mouth to your fingers and from your nails to your face and mouth."
It may seem ironic, but letting your nails grow starts with keeping them trimmed short to reduce the temptation to gnaw as you embark on stopping, says Dr Parsons.
Yet almost all nail biters have short nails and are simply waiting for a sliver to appear, so it is important to apply a bitter tasting coating to discourage the habit.
These are available without a prescription in most countries, and Dr Parsons also recommends getting regular manicures to keep the nails looking too good to chew.
Alternatively, she says, wearing gloves or putting tape or stickers over your nails works for those who prefer not to get manicures.
Find a stress ball and keep it with you for moments when you just gotta nibble, and try squeezing it instead, she says, and ask yourself what provokes the need to bite.
Some people are provoked by hangnails or unkempt hands whereas others do it out of boredom, stress or anxiety, so find out what gives you that urge to nosh on your nails, says Dr Parsons.
That way, you will know when to reach for your stress ball.
"For some people, nail biting may be a sign of a more serious psychological or emotional problem," she says. "If you've repeatedly tried to quit and the problem persists, consult a doctor. If you bite your nails and develop a skin or nail infection, consult a board-certified dermatologist."
If you find yourself taking one step forward and two steps back, that's just fine, according to Dr. Parsons, who recommends quitting gradually.
Try to stop biting one set of your nails, such as both of your thumbnails, and add other fingers little by little until you have stopped, she says.