7 gross things that happen when you bite your nails

Turns out nail-biting can be a sign of emotional imbalance, according to review in the American Journal of Orthodontics and Dentofacial Orthopedics (AJODO).

While it’s super common, nail-biting—or onychophagia, as experts refer to it—is a kind of “tell” that you’re freaked out or frazzled, and one that can spur other mouth-related stress behaviors like chewing pencils, biting your lips, or smoking.

That same review identifies a four-stage sequence common to anxious nail-biters: After raising the hand to the face or mouth and holding it there for a few seconds, the fingers are quickly tapped against the front teeth, the study authors say. Next, a series of quick spasmodic bitings occur, followed by visual inspection or feeling the newly bitten nails with your other fingers.

If that sequence sounds familiar, your habit may be an easy way to assess when you’re stressed out. 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, M.D., associate professor of dermatology at George Washington University.

If you needed seven more reasons to quit biting your nails, this list has you covered.

NASTY INFECTIONS

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.

“All our mouths are full of bacteria, so you can easily infect yourself,” Dr. Friedman says.

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. Dr. Friedman says biting your cuticles—the narrow crescents of skin that rim the bottom of your nail—is the most common cause of paronychia.

INFLAMMATION

Your saliva’s chemical composition allows it to break down fats and other food molecules, Dr. 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, Dr. Friedman says.

ILLNESS

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.

“Our hands come into contact with all kinds of debris and pathogens, and stuff tends to get stuck under our nails,” Dr. Friedman says. 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.

INGROWN NAILS

Your fingernails contain a generative layer called the “matrix,” which is sort of like the bed from which all your nail cells flower, Dr. Friedman explains. Biting or biting-related infections can damage that matrix, which could lead to chronic ingrown nails or nail deformities, he says.

FACIAL WARTS

Pick at a wart, and its contagious material can get onto or under your nails. Touch your face or mouth with those contaminated nails, and you could end up with warts on your face or neck, Dr. Friedman says.

HAND HERPES

Well, that’s not what it’s called, but that’s the idea. The actual condition is called “herpetic whitlow.”

If you have oral herpes—and roughly 40 percent of adults do—you can infect your fingers with the virus. That could result in fever, but usually the first symptoms are painful burning and tingling in your infected fingertips. After a week or two, you could also develop liquid- or blood-filled sores that will hang around (along with the pain) for another two weeks.

TOOTH PROBLEMS

The sockets that hold the roots of your teeth can be deformed or destroyed by chronic nail-biting, causing your teeth to become crooked. Nail-biting can also cause fractures in the teeth you use to do the nibbling, and can trigger the gum disease gingivitis, per another AJODO study. Teeth are pretty low maintenance, but here are the seven things you need to know about your teeth as you age.