The Hottest Thing in Head Lice

Our history of treatments is decorated with tragedy. But ivermectin just made a strong case for being this season's "it" neurotoxic hair lotion.

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When it's 2012, and we've put a car-sized robot on Mars, and we've sequenced 1,000 people's genomes (16 million file cabinets worth of data), it could seem odd that yesterday's New England Journal of Medicine also prominently reported an effective treatment for head lice.

Actually though, apart from the common cold, more elementary school kids in North America still get head lice than all other communicable diseases combined. And it's acceptable to get a cold, but it truly sucks to be the kid with lice.

SHARK300200.jpgNitpicking on Corregidor island, west of Manila [CherylRavelo/Reuters]

It's not that we didn't have good treatments before. We did, and still by various measures do, but the lice have been outgrowing them -- resisting, changing, nature, Jurassic Park, etc. The mainstay treatment, permethrin, now only works about half the time. For all our miniature iPads and hover boards, we were being outplayed by lice, on our own heads.

Even conceding, though, as Dr. Ian Malcolm posited, "life, uh, finds a way" -- when financial incentives align, we do reliably find excellent ways of destroying life.

In the beginning, eradicating head lice was approached mechanically. (Nitpicking means picking lice nits (eggs) out of one's hair). And then, thousands of years later, we're still physically combing and picking the nits out of our heads. The NIH recommends, as one non-pharmaceutical adjunct/approach, buying a fine-toothed metal comb from an Internet pet store, dipping it in beeswax, and combing thoroughly, for 7-10 days.

Meanwhile, again, Curiosity is on Mars.

For some, the mechanical removal comes all the way down to a bleakly formative shaving of their head -- as it did for the 8-year-old version of the now lovely but once abject Rebecca Greenfield of The Atlantic Wire.

There is also a medication called lindane, which made some people have seizures (so then you're not only the head lice kid, but also the seizure kid). And then a medication called malathion, which would nicely asphyxiate the lice, but had problems with odor and flammability. (The smelly kid with lice who had a seizure and once his head caught on fire.)

Other new treatments have shown promise, but the nice thing about ivermectin -- the medication studied in yesterday's NEJM paper (you may be familiar with it as an oral medication if you've ever had a nematode infection or scabies) -- is that it's an FDA-approved, one-time, 10-minute, DIY hair-wash; and that's it. No picking nits. The next day, 95 percent of the patients had zero lice. Which is especially nice because with lice it's not just about an itch, it's about get these off of my head immediately.


As a neurotoxin, ivermectin paralyzes and thereby kills lice. It flows over your hair, and the lice at first feel bathed, swaddled, and pleased. And then they start to shake, and convulse; and then they cannot move.

"How could something so creamy and smooth be so bad?"

"But that is all of life," drawls the ivermectin.

And then the lice feel their mouthparts cease to move, and they know they are defeated. The ivermectin then de-friends them on Facebook, and blocks them on Gchat and Twitter, just to make them feel terrible, then slumps away unapologetically. The lice are not simply defeated; they are destroyed.

Our children's children should grow up in a world without head lice. They should look back on our generation as the last of the lous-ed and smile, and shake their giant, futuristic heads. But as for 2012, consider how tremendously many more of us have had head lice than will be in any way involved with interplanetary rovers. Getting rid of head lice in ten minutes, instead of having to manually comb or pick them out of our heads like/with lower primates, is a genuinely and far-reachingly excellent proposition.