Help with head lice!!!!!!?

My 13 yr old daughter has been battling this for about 6 months now it is getting ridiculous. I hate it but of course she hates it worse. I've tried nix, rid, baby oil, mayo and now this comb that's supposed to zap them. Just when i think we are in the clear they reappear. she has thick shoulder length hair and i mean really thick. My doctor gave us a prescription called lundane or something like that but i haven't used it cause of all the side effects and the fact that it's been banned in alot of places. These little bugs are unbelievable it's like an epidemic. what can we do please help.