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.