I've been on mumsnet a lot of years and I continually see these threads about nits and various recommendations about this treatment or that treatment and I'm sorry but it's all bollocks.
You can spend fortunes on chemical treatments from Hedrin to tea tree oil or or sorts of concoctions but none of it means shit because your kids go back to school and they get re-infected.
You spend money, you clear them, they go back to school, they get nits again.
Instead of putting all that other chemical shite on their heads just make the comb/conditioner treatment a daily thing. Every time they bath/wash their hair.
It takes minutes and you will stay on top of any infestation and re-infestation.
Every day we have routines, showering, bathing, teeth brushing and so on, just make the comb/conditioner treatment part of that routine.
My kids took a bath, they washed their hair, they called me in, I sat by the bath and did the comb/conditioner treatment, wiping each comb through on a bit of bog roll and flushing it down the toilet.
My kids stayed nit free.
It's not rocket science, and it's not hard - just five minutes a day!!