How do Pyrethrin and Permethrin work?
Pyrethrin is a derivative of the Chrysanthemum flower. It is usually combined or synergized with piperonyl butoxide. Together the two chemicals act synergistically to kill lice, by acting on nerve cell membranes and interrupting signals travelling between the brain and the muscles. The lice/parasites become paralyzed and die because they are unable to breath. Pyrethrin also has some effect on the nits or eggs of the lice. Synergized pyrethrin has no residual effect meaning that none of the drug remains on the hair following treatment. Permethrin is a synthetic pyrethroid that is effective against lice, ticks, mites and fleas by acting on the nerve cell membranes interrupting signals travelling between the brain and the muscles. The lice/parasites become paralyzed and die because they are unable to breath. Permethrin has ovicidal activity and can also kill the nits or eggs of the parasites. Permethrin also has residual activity by remaining on the hair following treatment. Permethrin ha
