Is it normal to chew your toenails

When you bite your nails, those bacteria end up in your mouth and gut, where they can cause gastro-intestinal infections that lead to diarrhea and abdominal pain. Long-term, habitual nail nibblers can also suffer from a type of infection called paronychia, Scher says. Tears or abrasions in the skin of your fingertips allow strains of bacteria or yeast to get inside. Both cause swelling, redness, and a buildup of puss around and under the nail, which has to be drained surgically and treated with antibiotics or antifungal agents, he explains.

If the infection is bacterial, the nail can also become tender and painful. After infecting the fingers, these warts can then spread to your mouth and lips, Adigun adds. The perils of nail biting also extend to your teeth.

Nail biting, on the other hand, is often accompanied by pleasure — the people who do it want to do it, except for the fact that it causes damage over time.

Though people with OCD appear to have a greater chance of being nail biters , they seem to be distinct disorders. Recently psychologists have come to a more plausible theory of nail biting: that it can provide a temporary escape, distraction, or bit of pleasure or relaxation for the biter. Penzel points out that many people get the urge to bite when they're understimulated i. Like nicotine, the idea is that nail biting can have a biphasic effect: it can stimulate under certain conditions and relax in others.

It's still not proven, but to someone who's spent a lot of time biting her nails, this explanation rings true — and a recent study conducted by Sarah Roberts and other researchers at University of Quebec at Montreal provides a bit of evidence for it.

In the study, people with onychophagia, trichotillomania, or other body-focused repetitive behaviors were put into situations designed to elicit frustration they were given a difficult task that couldn't possibly be completed in the allotted time , boredom they were left in a room with absolutely nothing to do for a while , anxiety they watched a notoriously terrifying plane crash scene from the movie Alive , or relaxation they watched a video of a beach from a comfortable chair.

Obviously, these situations are somewhat artificial. Still, when the researchers observed the participants' behavior — and surveyed them afterwards on how strong their urge to bite was — they found something interesting. Other surveys of nail biters and hair pluckers have come to similar conclusions. Of course, this theory still prompts a more basic question: why does biting your nails — or plucking your hairs or picking at your skin — provide pleasure or distraction in the first place?

Why do so many people become addicted to these grooming habits, rather than, say, balling their hands up into fists? One possible answer relates to the finding that people with body-focused repetitive disorders tend to be perfectionists. It might be that ripping off an oddly shaped nail can provide a satisfying sense of perfection for the biter — and the quest for this satisfaction eventually gets out of control.

It's also possible that the uncontrollable urge to groom excessively goes much deeper than we realize. Lots of other animals, after all, seem to do it, too: some cats lick themselves excessively , leading to fur loss, while some horses bite their own flanks over and over.

Perhaps the urge to groom past the point of usefulness — to the extent that we actually cause damage to ourselves — is a trait that can be traced way back to the evolutionary ancestors we shared with these other mammals. Finally, there's a more mundane explanation. Maybe we just bite our nails because they're there. Psychologists believe that you can get psychologically not chemically addicted to pretty much anything : any activity that provides a reward can reinforce itself over time.

For an understimulated mind looking for a momentary distraction, the hands are always present. Biting and ripping off a nail can provide a distinct reward it sounds weird, but to a biter, there's something distinctly satisfying about removing it. Nails grow back, so there's always a fresh one to bite. Do it enough times, and you start to get pleasure from the habit — so whenever you're bored, stressed, or frustrated, your brain unconsciously goes back to it.

Different psychologists recommend slightly different techniques for quitting, but they mostly boil down to one common strategy: identifying the circumstances that lead you to bite, and changing them.

While that's sort of helpful— symptoms of stress can be silent or hard to identify —biting your nails can also lead to some truly gross or harmful health issues, says Adam Friedman , MD, associate professor of dermatology at George Washington University.

If you bite off too big a piece, you can expose the delicate skin beneath your nail, leaving it exposed to any bacteria or pathogens in your mouth—and there are plenty of them. One of the most common forms of infection is called paronychia, and it can cause swelling , redness, pain, and pus-filled lumps.

That infection can stick around for weeks at a time, shows a study in the journal American Family Physician. Friedman says biting your cuticles—the narrow crescents of skin that rim the bottom of your nail—is the most common cause of paronychia. Your saliva's chemical composition allows it to break down fats and other food molecules, Friedman says. While that aids your digestion , it can also damage and inflame the skin of your fingertips if you're constantly jamming them in your mouth, he says.

For the same reason, licking your lips can cause them to become chapped; your saliva is actually corroding the skin, Friedman says. Dealing with weak nails? Here are 8 reasons why your nails keep breaking. While exposing your fingers to the bacteria in your mouth is bad news, giving all the nasty microorganisms on your fingers access to your mouth is probably worse.

Put those germ-encrusted nails in your mouth, and there's no limit to the bad stuff that could result—from common colds to a serious stomach virus. Your fingernails contain a generative layer called the "matrix," which is sort of like the bed from which all your nail cells flower, Friedman explains.

Biting or biting-related infections can damage that matrix, which could lead to chronic ingrown nails or nail deformities , he says.