Clinical Consult: “Treatment resistant” head lice

head lice treatment resistant
(D. Kucharski & K. Kucharska/Shutterstock)

Lice are back in the news, and—with children back in school—are soon to be back in your office. While pediatricians generally view lice as a nuisance with no true medical consequences, families see lice as a time-consuming, worrisome health issue. One of the bigger concerns for parents is that if their child is diagnosed with lice, they will have to stay home from school or daycare.

Here are three important facts to keep in mind when discussing head lice with parents.

No. 1
Lice remain treatable.

The quickest, most efficient way to treat lice is to use one of the two ovicidal prescription creams, malathion or spinosad. In our practice we consider this pretty much a “one and done,” and sometimes a “two and done” (meaning the parent might have to repeat the cream treatment a week later).

Although it was initially considered ovicidal, recent studies have suggested that ivermectin is not completely so, in that it doesn’t kill the unhatched eggs (nits) but seems to kill the newly hatched nymphs. This may require a second treatment if live lice are seen a week after treatment.

Parents may bring up recent news suggesting that over the counter lice treatment products are no longer effective. Keep in mind that the study behind that news was funded by a manufacturer of prescription lice treatment products.

No. 2
Many parents prefer to use less “toxic” creams, of which there are several.

These creams—1 percent pyrethrin, 1 percent permethrin and 0.5 percent benzoyl peroxide—kill live lice but don’t kill nits. Often they have to be repeated to kill any lice that hatched after the first treatment; sometimes they even have to be applied a third time. Based on nits’ 8-to-10 day hatching cycle, reapplication every 9 days makes the most sense.

The U.S. Centers for Disease Control and Prevention has a wonderful description and treatment plan on its website that many parents find helpful. Directing parents to this website can help supplement your discussion. 

No. 3
Children should NOT be excluded from daycare or school based on a diagnosis of lice.

Both the National Association of School Nurses and the American Academy of Pediatrics disagree with no-nit policies. Generally, by the time a child has symptoms of lice (e.g., itchy scalp) they have been infested for three to four weeks, since it takes that much time to develop the allergic itching response to the lice saliva. So, to exclude that child from their usual daily activities is really too little too late. The best thing is to treat the child and to recommend a commonsense house cleaning.

One word on diagnosis: Recent pockets of resistant lice are causing many pediatricians to ask to see each patient with a suspected case of lice to confirm the parents’ diagnosis. It is not always easy for a parent to know if a child has lice, as dandruff, dust or dirt particles can look like nits to the untrained eye.

Susan Laster, MD, is a primary care provider in private practice in Brookline, Mass., and a member of the Pediatric Physicians Organization at Boston Children’s Hospital (PPOC).