Well yes, it is unhealthy for people to chew their nails. “Yes, and for a number of different reasons,” says Richard Scher, M.D., an expert on nail disorders at Weill Cornell Medical College and a member of the American Academy of Dermatology.
“Your nails harbor all sorts of germs. In particular, salmonella and E. coli — which tend to thrive in the cozy crevice beneath the tips of your nails,” Scher explains. When you bite your nails, those bacteria end up in your mouth and gut, where they can cause gastro-intestinal infections that lead to diarrhoea and abdominal pain. The ecoli is found in your bowels and this is a really nasty one. This can occur when people do not wash their hands after going to the toilet. You may wash your hands however if you have held hands or shaken hands with someone, are you sure they have washed their hands.
When you walk down the stairs do you happen to hold onto the hand rail? Most people do. So the last person who touched that hand rail may not have washed their hands.
The next time you are quietly listen to music, a lecture or watching TV, you may inadvertently slide your fingers into your mouth and that bacteria passes into your gut. This can make you very, very sick.
People who have been chewing their nails for quite a while can also suffer from a type of infection called paronychia. I am sure you can all relate to this one. You may see a bit of skin and think you can chew it or pull it off the skin and what happens it tears and it hurts. Or you may have abrasions in the skin around or close to your fingertips. These can allow bacteria or yeast to get inside. Both of these cause pain with swelling, redness, and can even lead to infections with puss around and/or under the nail. You may even need help with antibiotics or surgery.
Another nasty is the wart virus HPV and is also a common infection among nail biters, says Chris Adigun, M.D., a dermatologist at NYU Langone Medical Center. After infecting the fingers, these warts can then spread to your mouth and lips, Adigun adds.