You are all familiar with a scourge that has plagued mankind for centuries without relief in sight. It has attacked humans of all ages but predominantly targets children. It is currently the source of many missed school days as well as parental and school administrator distress. Of course I am talking about lice. For a condition that causes no significant illness it sure generates a lot of anxiety and excessive work.
The American Academy of Pediatrics recently revisited its guidelines around head lice and reviewed the current state of treatment. An important fact about lice was emphasized:
“[H]ead lice are not a health hazard or a sign of poor hygiene and are not responsible for the spread of any disease.”
And regarding treatment:
Optimal treatments should be safe, should rapidly rid the individual of live lice, viable eggs, and residual nits, and should be easy to use and affordable.
It is also important to understand the transmission of lice only happens via head-to-head contact. Lice cannot jump, only crawl. Even among those infected, one study showed only 4% of pillowcases were also infested. So the focus is on reducing lice on the scalp and the incidence of head-to-head contact.
Permethrin is the most common and well-studied treatment available and has very low mammalian toxicity. The 1% concentration (one brand is Nix) is available OTC. It should be applied to dry hair for 10 minutes and then rinsed off. Concern around developing resistance have led many providers (including my own practice) to use 5% permethrin, however incidence of resistance to 1% is not well documented and one study showed that lice resistant to 1% did not respond to 5%. Permethrin in the 1% and 5% strengths are on PHC’s formulary.
Pyrethrins (one brand is Rid) have been available since the 1980s and also have low toxicity but have fallen out of favor due to documented increased resistance.
Malathion, an organophosphate (brand Ovide) is actually more ovicidal and pediculicidal and typically only requires a single application (as opposed to permethrin, which may require retreatment in 7-10 days). However it has a high alcohol content (78% isopropyl) and can be flammable. Safety and effectiveness have not been established in children under 6 and it is contraindicated under 24 months.
Some newer treatments are benzoyl alcohol (brand Ulesfia) which works by asphyxiating the lice but is not ovicidal. It should not be used in neonates. Spinosad (brand Natroba) contains two fermentation products from a soil bacterium that appears to be both ovicidal and pediculicidal. It has been shown in one study to be much more effective than permethrin but is not approved for use under 4 years. Neither of these is on our formulary, though in the unlikely event permethrin fails, they can be requested.
Some other options are oral or topical ivermectin (the oral form is formulary) or occlusive methods like petroleum jelly or mayonnaise.
The mainstay of treatment has always been manual removal of lice and nits. While there is little literature to support its efficacy, it is indisputably safer, even given the minimal toxicity of most products. While “nit combs” are commonly found for sale, studies have found that type of comb is not as important as removal performed on wet hair after treatment. These studies show that lice removed by combing become damaged and cannot survive.
Regarding schools, it has been shown that nit screening is not an accurate predictor of who will become infested and live lice screening does not affect the incidence of head lice in schools. In addition head lice infestations have been shown to have a low contagion to other classmates. For these reasons, the AAP guideline (among many others) argues that “No-nit” policies should be abandoned.
So if you’ve been scratching your head wondering what to do for lice infestions, hopefully this will help!
Jeff Ribordy, MD