WipeOut attacks head lice by penetrating the lice and forcing the them to keep their orifices open. Head lice normally shut their bodies down when they sense moisture and they can essentially hold their breath for up to eighteen hours, but WipeOut has a proprietary formula that does not allow head lice to do this. WipeOut causes a physical reaction that kills head lice rather than a chemical one. The Pro Lice Comb should be used with WipeOut to remove nits and deceased lice after WipeOut has been applied and rinsed. WipeOut has NO chemicals or pesticides.