Nyda Express Against Lice & Nits Spray is designed to kill head lice and their eggs using a physical mode of action rather than chemical insecticide (knock down). NYDA® express contains two dimethicones (silicone oils), which seep into the breathing holes of lice and eggs, blocks their oxygen supply which rapidly suffocates and kills them. This physical mode of action means that even head lice and eggs which have built up a resistance to chemical treatments (knockdown resistance) are still eliminated.
