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Therapy for Head Lice

Head lice have plagued humans for years. While these parasites do not cause serious disease, the psychological and economic impact of their infestation can be significant. Various treatments have been tried, often with limited success, in controlling epidemics. These investigators reviewed all of the published trials of topical treatments for head lice.

To the authors' surprise, they found only 28 published studies. They included in their review those that they judged to have a low risk of bias and that measured cure rates at day 14; only 7 studies met these criteria. Cure meant that no live mites or nits were seen on physical examination, and day 14 was thought to be optimal because it allowed enough time for hatching of nymphs. (Some studies measured cure rates at 7 days, which these authors judged to be too soon.) The 7 selected studies evaluated eight different compounds and placebo. Overall, lindane and the natural pyrethrins, such as chlorphenamide and pyrethrin lotion, were not effective enough to justify their use. For malathion and carbaryl, the data were not sufficient to determine efficacy. Only permethrin creme rinse, with a one-time application, was determined to be effective.

Comment: Lindane shampoo and permethrin creme rinse have been the more popular treatments for head lice in the United States. Interestingly, lindane was found to be not very effective in well-designed, controlled trials. It is clear from this study that other compounds, such as malathion and carbaryl, need further study before their efficacy can be determined. At present, it appears that permethrin creme rinse (which is marketed over-the-counter in the U.S. as Nix) is the most effective treatment.

— K Wiss

Published in Journal Watch Dermatology November 1, 1995

Citation(s):

Vander Stichele RH et al. Systematic review of clinical efficacy of topical treatments for head lice. BMJ 1995 311 604-608.

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