Topical Ivermectin Lotion for the Treatment of Head Lice

Although head lice do not transmit disease, infestation causes pruritus, eczematization, social stigmatization, and school absence. Use of the first- line agents permethrin and pyrethrins is limited by emerging resistance. Lindane is disfavored because of neurologic toxicity, and malathion is flammable. Two recently approved agents, spinosad and benzyl alcohol lotion, are relatively expensive. Oral ivermectin has known efficacy when other treatments have failed. These researchers report the findings of two manufacturer-supported studies of topical ivermectin.

In multicenter, randomized, double-blinded, vehicle-controlled trials of a single dose of ivermectin 0.5% lotion without nit combing, a total of 132 index patients aged 6 months and older with three or more live lice (and more than 600 family members who had 1 or more live lice) received ivermectin lotion or vehicle alone. The primary end point was the number of patients who were louse-free by day 2 and remained louse-free through days 8 and 15. Ivermectin or vehicle was applied to dry hair and rinsed out after 10 minutes. In the intention-to-treat population, significantly more ivermectin recipients than vehicle recipients were louse-free on day 2 (95% vs. 31%), day 8 (85% vs. 21%), and day 15 (74% vs. 18%; P<0.001 for each comparison). Adverse events, including pruritus, excoriation, and erythema, occurred equally often with ivermectin and control (in approximately 1% of both groups).