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Options for treating drug-resistant lice


Lice are becoming more resistant to drugs. Understand the threat of resistant lice and the new ways to treat them.

Don’t be a louse: If you want to protect your patients against head lice, you need to understand the threat of these super-powered bugs-now often resistant to drugs-and the many ways to kill them off.

Lice are becoming more immune to over-the-counter drugs like Rid and Nix, says Raegan Hunt, M.D., Ph.D. Earlier this year, a study1 examined head lice in 48 states (all but Alaska and West Virginia) and found 98% had developed mutations.

The good news: “There are several fairly recently FDA-approved topical lice treatments that can be used to combat the resistant ‘super lice,’” says Dr. Hunt, a pediatric dermatologist at Texas Children's Hospital.

Dr. Hunt spoke about lice in an interview with Dermatology Times prior to her presentation at the summer meeting of the American Academy of Dermatology in Boston.

She offers these tidbits about the world of nits: head lice die in one to two days without feeding, and nits die within a week and cannot hatch if they are not near the scalp.

What can be done? Hygiene is helpful, she says. Machine wash and dry all clothing and bed linens worn in the two days before treatment. Items that can’t be washed should be placed in plastic bags for two weeks. Soak combs and brushes in hot water (at least 130°F) for five minutes. And vacuum the floor and furniture around where the infested person sits or sleeps.

Dr. Hunt also offers these pearls:

  • Lice move by crawling. They cannot hop or fly.

  • Pets do not play a role in transmission of human lice.

  • Nits alone do not indicate contagiousness.

  • Suspect sexual abuse if another kind of lice, pubic lice, appears in young or adolescent children.

Next: Treatments for resistant lice



  • Pyrethroids-pyrethrins like Rid and permethrin lotion 1% (Nix) -- may not work due to the development of drug resistance.

  • Malathion lotion 0.5% (Ovide) works in a single application for most patients, but is limited to those 6 and older. Resistance has been reported in the United Kingdom.

  • Ivermectin lotion 0.5% (Sklice) got FDA approval in 2012. It kills baby lice (nymphs) and works as a single application on dry hair without nit combing. It’s approved for children 6 months and older.

  • Spinosad 0.9% topical suspension (Natroba) was approved by the FDA in 2011. It’s approved for children aged 4 and up, and is also effective as a single application on dry hair without nit combing. Retreatment is usually not needed.

  • Benzyl alcohol lotion 5% (Ulesfia) received FDA approval in 2009 and requires repeat treatment on the ninth day. It’s approved for ages 6 months to 60 years.

  • Professional nitpicking services are available at $75-$100 an hour.

  • The AirAllé Lice Treatment, which uses heated air in a different way than a blow dryer, costs $170. One treatment is needed (it includes an hour of nit-picking and an hour of device usage), and it’s approved for ages 4 and up.

Keep in mind, Dr. Hunt says, that if you see large, live lice, they may be a sign of a reinfestation. Also, she says, lice of different sizes can be a sign of possible resistance.

And be aware of how lice may affect patients and their families. “Patients diagnosed with an infestation or their family members may express embarrassment that the diagnosis reflects poorly on their home cleanliness or personal hygiene,” Dr. Hunt says. “Additionally, prior partial treatments or treatment failures may result in patients feeling reluctant to accept the diagnosis and treatment plan. Being aware of and sensitive to these potential patient concerns helps facilitate communication about infestations.”


1. Yoon KS, Previte DJ, Hodgdon HE, et al. Knockdown resistance allele frequencies in North American head louse (Anoplura: Pediculidae) populations. J Med Entomol. 2014;51(2):450-7.

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