Lice is growing/has grown immune to the common treatments!
“Evidence indicates that the most widely used treatments for head lice (pesticide based shampoo) may be losing their effectiveness.” –USA Today 4/29/97
In a Harvard study, lice collected from Cambridge, Mass., Boise, Idaho, and the Philippines were placed on permethrin-soaked paper. The lice gathered from the Philippines (where such shampoos are not used) all died quickly. By contrast, the lice gathered from the US did not. Because of the resistance and product failure, some physicians have overreacted by prescribing repeated use of products, stronger formulas, or longer application times. History indicates that lice eventually grow resistant to every effective insecticidal treatment used against them.