How long of lice shampoo use would kill the lice?

Remove eggs. for a proper lice removal.use a product which kills lice and its eggs(nits). even 3 days of proper use put shampoo and wait for 4 hrs .then rinse after that comb with a fine tooth comb to remove the dead nits if other family members have it they should all be treated at the some time you may repeat this weekly for 3 times use RC spray on the bedding and furniture to kill the remaining eggs.