My 12 year old daughter and my 9 year old son BOTH had head lice last year. It was a nightmare. We used RID...TWICE! Both times, it returned. I suppose I didn't get all the nits out.
I eventually gave my son the shaved head look. Not down to the scalp....but close. Solved that problem.. Boys have that advantage. Take off the hair....problem solved. My daughter, however, was not so lucky.
I finally tried a home remedy (recommended by my neighbor). She slept in mayonnaise. Smuthered the things! We proceeded to have her sleep in mayonnaise weekly for 6 weeks. Lice cannot lay eggs until they reach a certain age (and I can't quite recall what I read, but I believe it was 2 weeks old) So, eventually, you will kill them all that way. It was alot easier that picking nits out of long hair.