Single Application of Topical Ivermectin is Effective for Eradication of Head Lice

DynaMed Weekly Update - Volume 7, Issue 46

Read the complete Weekly Update/earn CME credit The American Academy of Pediatrics recommends permethrin or pyrethrin insecticide as first-line treatment for head lice (Pediatrics 2010 Aug;126(2):392), but resistance to these agents has been increasing worldwide. Malathion, a common second-line option, has been effective in adults and older children, but it must be left on for 8-12 hours, and it is flammable and odorous. Furthermore, it is not recommended for children < 2 years old. Two recent identical randomized trials suggest that topical ivermectin may be an option for treatment of head lice when local resistance patterns or safety concerns limit the appropriateness of other agents. A total of 289 households were randomized in 2 trials to a single application of topical ivermectin 0.5% vs. placebo for each household member ≥ 6 months old with at least 1 live head louse. The youngest member of each household who had at least 3 live head lice was included in primary analysis (83% were < 12 years old). An extended analysis included patients in the primary analysis plus any other household member with at least 1 live louse (492 additional household members treated). The treatment was applied as a lotion to dry hair (by patient or caregiver), left on for 10 minutes, and then rinsed with water. No nit combing was performed. Data from the 2 trials were pooled for analysis. Patients were followed for 2 weeks. In the primary analysis, 94.9% in the ivermectin group were lice-free after 2 days compared to 31.3% in the placebo group (p < 0.001, NNT 2) (level 1 [likely reliable] evidence). The lice-free rate was also higher with ivermectin at 15 days (73.8% vs. 17.6%, p < 0.001, NNT 2). Ivermectin was also more effective in the extended analysis, with lice-free rates of 95.5% vs. 35.3% (p < 0.001, NNT 2) at 2 days and 78.7% vs. 22.2% (p < 0.001, NNT 2) at 15 days. In a subgroup analysis of 533 patients with pruritis at baseline, 66.7% in the ivermectin group were pruritis-free at 2 days compared to 42.6% in the placebo group. There were no significant differences in incidence of adverse events including pruritus, excoriation, or erythema (N Engl J Med 2012 Nov;367(18):1687). For more information, see the Head lice topic in DynaMed.