A mutated type of head lice has been found in 48 states, according to a recent academic medical study.
The so-called "super lice" is resistant to common, over-the-counter lice treatments like Nix shampoo.
The mutated bugs were found in every state except Alaska and West Virginia, which were the only two states that didn't send lice samples to the research team, according to the study published in the March 2016 issue of the Journal of Medical Entomology.
The aggressive lice has likely already been an issue for several years, as the samples used in the study were collected from July 2013 to March 2015.
Despite the bugs' growing resistance to some over-the-counter lice treatments, experts recommend still starting with those products and possibly trying several of them.
Clint Davis is a reporter for the Scripps National News Desk. Follow him on Twitter @MrClintDavis.