Nail-Biting Might Actually Be Healthy For Children


Parents who can’t get their kids to stop sucking their thumbs or biting their nails might rest a little easier knowing that these bad habits could protect their youngsters against allergies, according to a study published in Pediatrics.

Compared to kids who do not have these habits, children who bite their nails or suck their thumbs were much less likely to develop common allergies, researchers said. The study, however, does not encourage these habits. Rather, it only suggests that nail-biting or thumb-sucking may help protect kids against allergies into adulthood.

Image courtesy of Subharnab Majumdar on Flickr
Credit: Subharnab Majumdar/Flickr, CC BY 2.0

“Many parents discourage these habits, and we do not have enough evidence to [advise they] change this,” said Dr. Robert Hancox, study coauthor and Associate Professor of Respiratory Epidemiology at the University of Otago in New Zealand. “We certainly don’t recommend encouraging nail-biting or thumb-sucking, but perhaps if a child has one of these habits and [it] is difficult [for them] to stop, there is some consolation in the knowledge that it might reduce their risk of allergies.”

Rather, Dr. Hancox suggests that having a pet, such as a cat or dog, can also protect children from developing allergies.

Related: Give Peanuts to Infants? New Allergy Recommendations May Surprise You

The study’s findings provide more support for the “hygiene hypothesis,” which states that a lack of early childhood exposure to bacteria, infectious agents and probiotics increases a child’s likelihood of developing allergies and having a weak immune system.

The study followed 1,037 children born between 1972 and 1973 for more than three decades. By age 13, 38 percent of the children in the study who either bit their nails or sucked their thumbs were allergic to dust mites, different types of grass or dog dander. Whereas 49 percent of the children who did not bite their nails or suck their thumbs developed those allergies. Only 31 percent of children who both bit their nails and sucked their thumbs developed allergies.

Other experts, like Dr. Alison Morris, professor of Medicine in the Division of Pulmonary, Allergy, and Critical Care at the University of Pittsburgh and Director of the university’s Center for Medicine and the Microbiome, are a bit skeptical about the study’s findings.

“If parents can’t get their kids to stop sucking their thumbs, this may make them feel better about that,” Dr. Morris told Today. “But I don’t think the study offers anything actionable at this point other than to be more relaxed about children’s exposures to germs.”

Related: This Woman Is Deadly Allergic To Nearly Everything — Including Her Husband

Danielle Tarasiuk

Danielle Tarasiuk is a multimedia journalist based in Los Angeles. Her work has been published on, Yahoo! Sports, KCET, and NPR-affiliate stations KPCC and KCRW. She’s a proud Sarah Lawrence College and USC Annenberg alumn.