Treatment of head louse infestation with 4% dimeticone lotion: randomised controlled equivalence trial.

OBJECTIVE To evaluate the efficacy and safety of 4% dimeticone lotion for treatment of head louse infestation. DESIGN Randomised controlled equivalence trial. SETTING Community, with home visits. PARTICIPANTS 214 young people aged 4 to 18 years and 39 adults with active head louse infestation. INTERVENTIONS Two applications seven days apart of either 4.0% dimeticone lotion, applied for eight hours or overnight, or 0.5% phenothrin liquid, applied for 12 hours or overnight. OUTCOME MEASURES Cure of infestation (no evidence of head lice after second treatment) or reinfestation after cure. RESULTS Cure or reinfestation after cure occurred in 89 of 127 (70%) participants treated with dimeticone and 94 of 125 (75%) treated with phenothrin (difference -5%, 95% confidence interval -16% to 6%). Per protocol analysis showed that 84 of 121 (69%) participants were cured with dimeticone and 90 of 116 (78%) were cured with phenothrin. Irritant reactions occurred significantly less with dimeticone (3/127, 2%) than with phenothrin (11/125, 9%; difference -6%, -12% to -1%). Per protocol this was 3 of 121 (3%) participants treated with dimeticone and 10 of 116 (9%) treated with phenothrin (difference -6%, -12% to -0.3%). CONCLUSION Dimeticone lotion cures head louse infestation. Dimeticone seems less irritant than existing treatments and has a physical action on lice that should not be affected by resistance to neurotoxic insecticides.