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Ivermectin for Head Lice: Lotion and Oral Options

Ivermectin 0.5% lotion is FDA-approved for head lice (Pediculus humanus capitis) in patients six months and older. It is applied once, left on for ten minutes and rinsed out, and unlike older treatments it does not require nit combing or a second application. Widespread resistance to permethrin and pyrethrin has made it an increasingly important option.

Why a single application works

Most older pediculicides kill live lice but not eggs, which is why they demand a second application 7 to 9 days later plus laborious nit combing. Ivermectin lotion behaves differently: lice that hatch from treated eggs are unable to feed and die of starvation, because ivermectin paralyses the pharyngeal pump they use to take blood.

This is what allows a single ten-minute application to succeed where older agents needed a repeat course.

Trial results

In two pivotal randomised, vehicle-controlled trials, roughly 74 to 76 percent of patients treated with a single application of ivermectin 0.5% lotion were louse-free at day 15, against about 18 percent with vehicle. Notably, participants were instructed not to nit comb, so the result reflects the lotion alone.

Resistance to older treatments

Surveys across North America and Europe have found very high frequencies of knockdown-resistance mutations in head lice, which confer resistance to permethrin and pyrethrins. In many regions the great majority of lice now carry them. This is the practical reason ivermectin and other newer agents have moved up the treatment order.

Oral ivermectin for head lice

Oral ivermectin at 200 to 400 micrograms per kilogram, repeated after 7 to 10 days, is used off-label for difficult or repeatedly failed cases. A trial in patients who had already failed topical therapy found oral ivermectin superior to malathion lotion. It is generally reserved for treatment failures rather than first-line use.

Human pharmaceutical ivermectin, shipped from the USA

GMP-certified human formulations — tablets and 1% cream. Never veterinary products. Most USA orders ship within 1–7 business days.

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Frequently asked questions

Is ivermectin approved for head lice?

Yes. Ivermectin 0.5% lotion is FDA-approved for head lice in patients six months and older, as a single ten-minute application.

Do I still need to comb out nits?

No. The pivotal trials specifically instructed participants not to nit comb, and still showed roughly 74 to 76 percent louse-free at day 15. Lice hatching from treated eggs cannot feed and die.

Why are permethrin treatments failing?

Head lice across North America and Europe now carry knockdown-resistance mutations at very high frequency, which confer resistance to permethrin and pyrethrins. This is why newer agents including ivermectin have become more important.

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Medical information notice. This page is provided for general information and reflects published research and regulatory guidance at the time of writing. It is not medical advice and is not a substitute for consultation with a qualified healthcare professional. Dosing decisions, drug interactions and treatment choices should be made with a clinician who knows your history.