This article originally appeared on Tonic.
The Scenario: When she’s nervous, your friend chows down on a ten-course meal of fingernail with a side of skin. On closer inspection you notice she’s chewed every nail, picked at her cuticles, and torn off the surrounding skin like a wild animal tearing apart its prey. You plead with her to stop, but she’s tried everything: the gross-tasting nail polish designed to repel biters, the rubber band around the wrist—you name it.
You’re concerned about the germs your friend might be ingesting, and the fact that she routinely gnaws at her fingertips until they bleed. Is her unbridled nail biting merely a nervous habit, or is it a sign of something more troubling?
The Facts: Habitual nail biting, also known as onychophagia, is a common disorder that affects 20 to 30 percent of the population. Biting your nails compulsively has wide-ranging health implications that can affect multiple organ systems, says John Yost, clinical associate professor of dermatology at Stanford Health Care and director of the Nail Disorders Clinic (yes, this is a thing). “We often carry pathogenic bacteria on or under our fingernails, and biting them obviously provides a direct pathway for the bacteria to get into your gastrointestinal system.” Nail biting can also increase the spread of unpleasant viral infections like warts and herpetic whitlow (an abscess on your hand) between the mouth and hands, and can chip or cause misalignment of the teeth, Yost says. “But, this is more than just having a bad habit you can’t kick.”
Your friend’s habit is considered a body-focused repetitive disorder, alongside the likes of trichotillomania (hair pulling) and dermatillomania (skin picking). “All of these disorders involve a hand, and all of them are, to some extent, automatic and out of control,” says Kieron O’Connor, a professor of psychiatry at the University of Montreal and director of the OCD Spectrum Study Center. “People call them nervous habits, but often they’re not linked to nerves or anxiety, more so to the frustration spectrum of emotions.”
What Could be Going on in Your Friend’s Head: Does your nail-biting buddy have unrealistic standards? Does she tend to over-prepare, or try to accomplish too much at once? Well, there’s a good chance she might be a perfectionist. In his 2015 study, which looked at the impact of emotions on body-focused repetitive behaviors, O’Connor and his peers found that perfectionism was a characteristic spanning all BFR behaviors. “Perfectionism has different dimensions, but one aspect that seems to play into these repetitive habits is that the person is quite self-critical—they have very high standards and can easily become frustrated or dissatisfied with themselves,” he says.
While often associated with stress relief, nail biting also has to do with the regulation of emotions, O’Connor says. “People with these sorts of habits tend to be less good at recognizing their emotions and coping with negative emotions, so one way of doing this is to get involved with a repetitive behavior, which initially produces some sort of comfort but has very destructive implications, and then they feel guilty or ashamed—a negative emotion—which fuels their self-criticism,” O’Connor explains. “It’s a vicious cycle.”
The Worst That Can Happen: Worrying about your friend’s general health as a result of her nail biting isn’t unwarranted. “By biting your nails, you’re basically licking whatever your hands have come into contact with throughout the day if you haven’t washed them thoroughly, whether it’s a public door or the lever for flushing a toilet—just think of yourself licking that surface,” Yost says.
And by biting the skin around her nails, your friend is increasing her risk of bacterial, viral and fungal infections, which could spread to the bloodstream or affect the bone underneath the skin around the nails. And while this doesn’t seem as dire as falling deathly sick from some obscure infection, she could also end up with some pretty nasty looking fingernails. “People who bite the skin around the nails can get hangnails, or what’s termed paronychia, which is an inflammation of the lateral or proximal nail folds," Yost adds. "Chronic inflammation of that skin can cause scarring of the nail matrix—the group of cells directly below the cuticle where your nail is made—which leads to permanent deformity of the nail." This could be a nail furrow—ridges that run lengthwise or across the nail—or permanent splitting or cracking of the nail.
What to Tell Your Friend: While the home remedies do work for some people, in more serious cases, your friend should probably have a chat with her therapist, who will likely help to identify the triggers and work out how to redirect that energy to another, more productive behavior. Kicking the habit can be done, O’Connor says, but not without difficulty. “People tend to think habits are just a question of willpower, but it does actually take some time, and the person really has to be motivated to make it happen.”
One of the more common psychological treatments for nail biters is habit reversal, which requires the patient to become aware of when the behavior is about to occur and perform an opposing action, such as putting their hand in their pocket and making sure it’s not going towards their mouth. If your friend is more of a DIY kind of gal, she could try this method at home. O’Connor recommends keeping a record of the situations that produce the urge to bite, and trying to address the emotions or actions that precede the biting.