Choice of treatment will depend on local patterns of resistance

The treatment of head lice is now complicated by the emergence of resistance to pediculicides. Most clinical trials were done before resistance emerged and reviews of these trials do not give clear guidelines to the clinician. In these circumstances, the choice of treatment will depend on local patterns of resistance, and where treatment has failed, recourse to testing for resistance is perhaps the best way forward.

Human head lice (Pediculus capitis) are ectoparasites with an obligatory blood feeding habit, which requires them to feed on their host's blood several times each day. Juvenile and adult forms both occur on the scalp, and eggs are attached to the hair shafts near the scalp. Infestation with head lice is a widespread condition that is seen most commonly, but not exclusively, in children of school age, although there is no proof of a link with school attendance. Prevalence does not vary significantly with season, and variations are …