We just went through this.
I really wanted to avoid the Nix/Rid stuff because I'm breastfeeding, plus I'd heard that lice are becoming immune to the stuff. So we did the natural remedies. Oil/vinegar/essential oils on the head over night. The oil suffocates the lice, the vinegar loosens the eggs from the hair shafts. Then I went through my kids' hair, my mom and my husband went through my hair. Hellish, that was. Found nothing. Gave my kids crew cuts (sob). Did the whole damn treatment again. Washed everything a zillion times on hot, dried on hot, and bagged up nonessentials or things that couldn't be washed. Tried mayonnaise. Tried peroxide. Tried the oil yet again.
Well, the problem was that we apparently weren't getting all the eggs. I was about this close >< to shaving my entire head. Then we tried hair dye. The whole family just to be safe, even though it was only myself and my son who were itching. 20 minutes of hair dye on the head, and that was it. Apparently the ammonia killed the unhatched lice. YAY! Well, later that day my FIL brought over an article about this woman who nit-picks for a living. She uses conditioner, that's it. So, because I didn't know yet that the dye had killed off all the beasties, I put conditioner into my son's hair and let it sit for about 15 minutes, then combed through, and imagine my shock when the eggs started floating up to the surface as I combed! Wow! So now, if this ever happens again and I don' t want to use hair dye I know what to do to get those damn eggs.
Anyway, we didn't do the conditioner trick on me, and the lice were truly truly gone so we know that the hair dye did it. Unfortunately, my scalp by this time was fried, and I had phantom itchies for about a week. But, the lice are truly gone. Hallelujah.