Trying to Keep Ahead of Lice: A Therapeutic Challenge

C. E. Malcolm, MD, CCFP; J. N. Bergman MD, FRCPC


Skin Therapy Letter. 2006;11(10):1-6. 

In This Article


Malathion is an organophosphate cholinesterase inhibitor that causes respiratory paralysis of the louse. It is a fast acting pediculicide that presently has the highest ovicidal activity. It binds to the sulfur atoms of the hair, accounting for its residual effect. Malathion 0.5% can be applied for 10 minutes or overnight and repeated in 1 week. It has an unappealing odor and can cause stinging of the skin and eyes.[5] This product should be used with caution, as its base is flammable and may lead to respiratory depression if ingested (although there are no reported cases).[4] Currently significant resistance to this agent has not been reported in the US, but may occur with ongoing use as seen in other countries.[8]


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