Parents with kids heading back to school have a new worry this year: super lice. Research now suggests that the vast majority of lice in the U.S. are resistant to the insecticides used in popular over-the-counter products such as Nix and Rid.

In a study published in the Journal of Medical Entomology earlier this year, researchers collected lice from 138 communities in 48 state. They found that in 132 of them the lice tested were resistant to permethrin, the active ingredient in Nix, a creme rinse.

The findings would almost certainly be similar for Rid, a shampoo that contains the related compound pyrethrum, says J. Marshall Clark, Ph.D., a professor of environmental toxicology and chemistry at the University of Massachusetts at Amherst and the study’s principal investigator.

Consumer Reports reached out to the makers of Nix and Rid. Rid did not respond. Nix says its active ingredient is still recommended by the American Academy of Pediatrics. A spokesperson for the American Academy of Pediatrics says that the organization is not yet changing its recommendation, adding that the AAP continuously reviews "the scientific research."

The best way to get rid of lice is not with these shampoos.
Research suggests that most lice are resistant to the active ingredient in these over-the-counter products.

The Problem With Prescription Remedies

Some prescription lice treatments might also pose problems, says Michael Hansen, Ph.D., a senior scientist at Consumer Reports. Particularly worrisome: shampoos containing lindane.

Consumer Reports petitioned the Food and Drug Administration to outlaw that neurotoxic pesticide as a lice treatment as early as 1981, and wrote the agency again in 2015, after lindane was found by the World Health Organization to be carcinogenic to humans. Despite reports of seizures and even deaths from improper use of topical products containing lindane, it’s still on the market as a prescription drug for lice.

What to Do Instead

Wet combing is the best way to get rid of the pests, Hansen says:
• Coat your child’s hair and scalp with conditioner or a lubricant (olive oil will work).
• Use a wide-tooth comb to separate hair into sections.
• Follow with a metal nit or flea comb, concentrating on the area close to the scalp.
• After each comb-through, wipe the comb on a paper towel and inspect for lice. Repeat every day until no live lice are seen, then every few days for about a month.

Read more about how to get rid of lice and watch the video, above.

Editor's Note: This article also appeared in the September 2016 issue of Consumer Reports magazine.