t’s a ground-breaking treatment – designed to eradicate lice and their eggs (nits) in a single application, and scientifically proven to kill head lice in one minute and their eggs in eight hours – and it’s NHS-approved for prescribing. NYDA® is a clear liquid (92% dimeticone dual formula) that works physically – it does NOT use chemical neuro-toxic pesticides to poison head lice and their eggs. Instead, it kills lice by suffocating them.