How to Treat Head Lice

- Nite (egg) removal is the key step -

Summary: Head lice and pubic lice infestations can be eliminated by careful nit removal plus treatment of live lice with medicated shampoos or rinses. Treatment failures can often be traced to incomplete nit removal rather than so called "pesticide resistance".

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

Treating lice = kill active lice + nit removal

Every louse infestation, whether head, body or pubic louse, should be treated in the same way. First kill active lice then crush and/or remove nits (eggs). Nits can be combed out of the hair with the proper type of comb, or washed from clothing in the case of body lice. Live head or pubic lice can be killed with medicated shampoos/rinses.

Since lice don't live for very long off their host it is not necessary to excessively clean the house and bedding. Also, since body lice are easily treated by simply washing clothes the following information pertains mainly to head lice only (see What are Body Lice? for information about body lice infestations)

human louse

human body louse (very similar to head louse); about 2 mm (1/16") long

First, kill live lice

This is the first step but it is not the most important step. Most live lice (immature and adult lice) can still be killed with medicated shampoos or rinses that contain either pyrethrum or permethrin (see Picking a Shampoo or Lotion). While there are reports of insecticide resistance to both medications lice shampoos/lotions are still more or less effective. This is still my first choice for eliminating live lice. Any lice that survive will be removed in the next step.

Then, crush and remove nits

After treating hair to kill as many live lice as possible use a good, fine-tooth, metal lice comb to crush and remove nits and any remaining live lice. Carefully comb through hair paying particular attention to the hair on the back of the head and neck and around the ears. Comb a small bunch of hair at a time and some "nit-pickers" will pin back the hair that has been combed to keep track of their progress.

Nit-combing can take 1 to several hours so be patient. Don't use the plastic combs that come with some shampoos and rinses, use a metal lice comb instead (see How to Pick the Best Lice Comb). You also might want to use one of the nit-combing aids that de-tangles and lubricates hair to make combing easier . These products can make nit-combing significantly easier and faster. That's it. Be sure to follow package instructions carefully.

What is still debated about treating lice?

A few things about head lice are still debated by parents and teachers. (1) Whether or not "no-nit" policies in schools are effective. More people and even the American Academy of Pediatrics (see recent report here) are coming around to the idea that these policies are not effective and may even be damaging. (2) Whether or not head lice are resistant to pyrethrum and permethrin, the medication in products like Nix (tm) and RID (tm). (3) Whether or not shampoos and rinses containing insecticidal medications are safe. And, (4) whether or not alternative head lice treatments are useful.

Here's my opinion ...

(1) I do not advocate "no nit" policies in schools but do sympathize with schools trying to get parents to properly treat children that have head lice.

(2) According to scientific studies from 1999-2002, some head lice populations in the US show resistance to permethrin (see What is Pesticide Resistance?). While some resistance has been identified not every population exhibits this characteristic so with a newly confirmed infestation the first choice for treatment should still be one of the over-the-counter (OTC) shampoos/rinses containing permethrin or pyrethrum.

(3) Insecticide-based shampoos or rinses are safe and effective if used according to instruction. However, do not use products containing lindane as safer medications are now available. Use products only as directed by the label.

(4) Don't assume that "alternative" means non-toxic. There has been very little formal testing of the many
alternative treatments for head lice. Oil or hair conditioner-based products probably work by improving the efficacy of nit combing. Products containing essential oils probably help with nit combing as well.

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