If you can avoid putting chemicals on your head, I recommend you do it! So then how do you deal with lice? Try these ideas from Rainbow Riders Trading Post:

“Lice can be killed quickly, easily, cheaply and safely with mayonnaise. Simply get a new jar of mayonnaise (not Miracle Whip) from your kitchen shelf or at the grocery store. (Don’t grab one from the refrigerator, as it will be way too cold.) Grab a handful (or several) and cover all of your child’s hair, being sure to get behind the ears and down the neck a little. You can cover this with a plastic shower cap to keep the mayonnaise from dripping or getting onto your furniture. Leave the mayonnaise on for two hours to smother the lice and developed eggs. Then, remove the shower cap and throw it away, both of you wash your hands good with soap, and shampoo the hair thoroughly. It may take two or more shampoos to get the hair clean."

Photo CC 2.0, jessamyn