Head lice: over-the-counter treatments becoming less effective

Head lice may affect millions in the United States each year. They are not a health hazard or a sign of uncleanliness, though they are a source of embarrassment and are the cause for many lost days of school and millions of dollars spent on remedies.

According Dr. Kyong Sup Yoon from Southern Illinois University Edwardsville and Dr. John Clark from University of Massachusetts Amherst, lice in at least 25 different states showed resistance to common over-the-counter (OTC) treatments. In their analysis of 109 different lice populations from 30 different states, 95 percent of them had high levels of gene mutations that have been linked to resistance to pyrethroids — a chemical family that includes pyrethrin and permethrin, the respective active ingredients in the popular OTC lice remedies Rid and Nix.

Do the results come as a surprise to most scientists and pediatricians? Not really. If you give the same medication over and over, you are bound to have resistance. Yes, one could say that there was potential for some bias in their study (given the funding party also makes a prescription lice treatment). I would have to agree that in my clinical practice in Kentucky — one of the 25 states with noted resistance — I have seen OTC products fail to effectively treat head lice. However, parents don’t call whenever they treat their kids at home with OTC products and they do work! It’s unfortunate, but many insurance companies mandate that a patient first be treated with an OTC remedy and fail this approach before authorizing a prescription product (such as Ovide, Ulesfia, Natroba, and Sklice).

So what’s a parent to do? Skip the OTC medication and call up your pediatrician? No. Remember, even though head lice are a nuisance and cause high anxiety for parents, it’s not technically a medical problem. These “super lice” are just lice. There’s nothing super terrifying about them at all. Try the OTC product first. If it doesn’t work, get a prescription strength medication. Ask your child’s pediatrician about the resistance pattern of head lice in your community. The authors of the study, for instance, found no resistance in Michigan!

Besides treatment failure due to resistance, possible reasons for persistent head lice may include misdiagnosis (mistaking dandruff, hairspray droplets, scabs, dirt, or other insects for head lice), noncompliance with therapy, or simply reinfestation.

The best treatment is prevention. Avoid sharing personal items like hats, combs, and brushes. Lice crawl and transmission can only occur if someone comes into direct contact with the head of an infested individual. Occlusive substances such as mayonnaise, tub margarine, herbal oils, and olive oil anecdotally may work but no good studies have been conducted to prove their effectiveness. Flammable substances like kerosene or gasoline should never be used.

The American Academy of Pediatrics (AAP) and the National Association of School Nurses (NASN) recommend not sending children directly home if lice has been found. Unfortunately, many school systems refuse to accept the notion that lice are not a medical hazard and pose no serious risk to others.

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About Dr. Justin Morgan, Bundoo Pediatrician

Justin Morgan, MD, FAAP, is a board-certified pediatrician who practices general pediatrics in Louisville, Kentucky. He cares for children of all ages.


  1. My skin is crawling… and I can’t shake the mental image of lice wearing masks and superhero capes.


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