A comparison of a single occasion treatment of head louse infestation with phenothrin liquid shampoo or a carbaryl lotion.

Fifty subjects with head louse infestation were recruited into a controlled trial to compare a phenothrin liquid shampoo with a carbaryl lotion. Twenty-seven subjects were treated with phenothrin and 23 with carbaryl, each formulation being applied only on a single occasion. Subjects were inspected for evidence of live lice and eggs at 24 hours and 3 to 4 weeks after application of treatment. The results showed that both the phenothrin liquid shampoo and the carbaryl lotion were effective in killing adult lice and viable eggs. No statistically significant difference in treatment efficacy was observed between the two groups. Fewer side-effects, however, were observed with the phenothrin liquid shampoo than with the carbaryl lotion. These results indicate that, when applied as a single treatment, a phenothrin liquid shampoo was as effective as a carbaryl lotion in eradicating head lice and eggs.