What I use to beat head lice
Dove Oil Conditioner. Main ingredient is Dimethicone which makes the nits and lice come out easily.
How I use it
The conditioner doesn't kill anything but it makes the lice & nits come out of the hair easily. We did two rounds of pesticide shampoo w/ no success. We put a lot of the conditioner on her hair while wet and then used the wide tooth nit comb to go through her hair, then I rinsed the comb in a white bowl filled with water so I could see the nits and lice. We did several passes until nothing came out any more. Then I picked through her hair and pulled any eggs that were still stuck with my fingernails. We did this each night for a week and then every few days after that. It was tedious but not hard but it worked and was very inexpensive.
I would not even bother with any type of pesticide shampoo again. They are harsh chemicals and they don't really work. We used Nix first which said that it killed the eggs too. It did not work and neither did Rid which comes with a nit removal gel that just got hard in the hair after a few minutes and didn't make the eggs easier to remove. I read about Lice MD which uses Dimethicone so I went around the house looking for conditioner that had Dimethicone. We started with a Pantene that had it but switched to the Dove because it had more Dimethicone in it and was thicker and easier to work with.