Comparison of wet combing with malathion for treatment of head lice in the UK: a pragmatic randomised controlled trial

Background Concern about the effectiveness and toxicity of insecticide lotions has led to promotion of mechanical methods to remove head lice. We compared the effectiveness of “bug-busting” (wet combing with a fine-toothed comb) and malathion lotion. Methods We screened 4037 schoolchildren in two counties in Wales, UK (intermediate resistance to malathion). Of 167 found to have head lice, 81 (aged 3–14 years) were eligible to participate in a randomised controlled trial that compared mechanical removal of lice by a commercial kit every 3–4 days for 2 weeks with two applications of 0·5% malathion lotion 7 days apart; parents carried out both treatments. The outcome measure was the presence of live lice 7 days after the end of treatment. Analyses were by intention to treat. Findings 74 children completed the study and 72 were included in the analysis. The cure rate was 38% (12 of 32) for bug-busting and 78% (31 of 40) for malathion. Children assigned bug-busting were 2·8 (95% CI 1·5–5·2) times more likely than those assigned malathion to have lice at the end of treatment (p=0·0006). Interpretation Malathion lotion was twice as effective as bug-busting, even in an area with intermediate resistance. Policies advocating bug-busting as first-line treatment for head lice in the general population are inappropriate. Assessment of the outcome of treatment 1–2 weeks after completion is essential for successful management. Only about 50% of participants complied fully with treatment, so future trials should be pragmatic in design, avoid false incentives, and study representative samples of children.