Standard treatments for head lice are available without prescription. Products such as RID and NIX as usually effective. The products contain permethrin, natural pyrethrins, or organochlorine insecticides. Remaining nits which are firmly attached to the hair can be loosened by soaking the hair with vinegar for at least five minutes. Then a fine tooth comb or a nit comb can be used to remove the nits.

During recent years, an increase in head lice treatment failures has been reported in different areas of the world. Most failures to cure the head lice come from re-infection or not following the package directions. However, there also has been a recent increase in the lice resisting these agents. We don't know why this has happened, but the lice are becoming more immune to the insecticides. It appears that the products containing permethrin are more prone to the resistance problems.

Newer topical treatments which have been approved by the FDA and are available by prescription include malathion lotion (Ovide), benzyl alcohol lotion (Ulesfia), spinosad suspension (Natroba) and ivermectin lotion (Sklice).

Oral treatment with ivermectin has been recently used in the treatment of head lice infestation that is resistant to other treatments. Ivermectin is an antiparasitic drug discovered in the early 1970s and has been widely used in the treatment of intestinal parasites (worms) in man and animals. The FDA has not yet specifically approved the oral form for head lice treatment.

Ivermectin is toxic to only to arthropods (bugs) and nematodes (worms), in which it induces paralysis of the pharynx and leads to starvation that may subsequently kill the parasite. There have not been adequate studies to establish the drug's safety in pregnant women or in children weighing less than 30 pounds, but there are no known serious side effects. A single dose is about 75% effective. The results are better when ivermectin is used in combination with a nit comb and when all the family members are treated.

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