Prevention, Detection, and Treatment of Head Lice

Mother combing daughter's hair with nitcomb
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Head lice are parasites that feed on human blood and bask in the warmth of the noggin. They make new baby lice by laying eggs (called nits) attached to hair follicles. The good news is that no known diseases are carried by common head lice. The bad news? Well, they're ugly little creatures that make you itch just by reading this (go ahead and scratch; I'll wait). 

Live Head Lice 

Live head lice grow to be about the size of a grain of rice, are dark-colored and will run from the light, so it's not that easy to see them.

If you do, they'll probably be on the move, and moving head lice are definitely alive. To find live head lice, separate the hair all the way down to the scalp and look for movement.

Of course, head lice are good at going undetected. Thankfully, there are other ways to identify an infestation:

  • Nits are the eggs lice lay on the hair shaft. Look for a bunch of nits. You can tell the difference between nits and dandruff by how hard it is to get them off the hair. Nits hold on -- dandruff doesn't.
  • Go to the doctor. Your physician can see if you have an infestation by looking for other signs -- like lice poop. Your doctor can also use a Woods lamp to search for nits.

Nits are like lice; it's the warmth of the scalp that keeps them alive. Finding nits isn't enough to determine if there's a current infestation. Nits can hold on for up to six months. If nits haven't hatched by the time hair grows more than half an inch, they probably won't hatch at all.

Lice and School 

Some schools have policies that restrict students from attending if they have nits or lice. According to the CDC, many of these policies go way too far. In fact, as soon as an active infestation is treated, kids should be allowed to return to school.

It's not as easy to spread lice from one person to another as we used to think.

Kids pretty much have to hug an infested child to get the critters. They can't hop or fly. They just crawl. Without noggin-to-noggin contact, it's really hard to spread head lice. Even sharing clothing or combs is not likely to spread the infestation.

You'll have to check with your school officials, however, to know whether a child will be allowed back to school with visible nits. Chances are, the school is going to be a lot stricter than the CDC.

Head Lice Treatments

Only active infestations need to be treated. Treating head lice is a labor of love. No matter how you do it, there will be some serious nit-picking going on.

Lice-killing shampoo is the most common treatment for head lice. There are two lice shampoos sold over-the-counter and two prescription versions.

Treatment with lice-killing shampoo only kills live head lice. Here's where the labor comes in. Nits don't die and will have to be removed manually. Use a nit comb or flea/tick comb to get the little buggers.

For the next 10-12 days, you must be diligent and keep a watchful eye for more nits. They're hard to find. As you see them, remove them.

Depending on the lice-killing shampoo used, you will probably need to do a second treatment about 10 days after the first.

There are some alternative treatments for head lice. The simplest is just to comb through wet, conditioned hair with a nit comb and remove all the nits you see (usually referred to as either "bug busting" or "wet combing"). Keeping on nit patrol will keep new head lice from hatching as the older lice die. Eventually, the infestation will die off. It's a slow process, but it is the most natural and may well be more effective than lice-killing shampoo. Minus the wet hair and conditioner, this is the way monkeys do it.

"Natural" products are also available. Tea tree oil is preferred by some to lice-killing lotions and shampoos.

Regardless which method you choose, picking nits is going to be part of the solution.

Preventing Re-Infestation

Head lice like it hot. They don't live long away from the heat of the scalp. It's probably good enough just to carefully clean the clothing and bedding an infested person used.

On one hand, the CDC says to clean any bedding or clothing an infested person used in the last 48 hours. Presumably, that means anything used more than 48 hours ago is safe, which is directly at odds with the CDC's recommendation on what to do with items you can't wash. The CDC says to bag items like stuffed animals for 2 weeks. I have an idea: Just don't let infested kids cuddle with their favorite stuffed bear for at least 3 days and call it good. It wouldn't hurt to run a vacuum over the teddy bear just in case.

Indeed, it wouldn't hurt to run a vacuum over the infested person's bedroom and furniture, either.

As far as washables:

  • Wash in hot water (130 degrees or more) any bedding or clothing used by an infested person within the last 2 days. If it can't be washed, then dry-clean it.
  • Soak combs and brushes in hot water (130 degrees) if you haven't already done that.
  • Stay away from spray fumigation products; they can be toxic and they aren't necessary.

Don't worry too much about re-infestation. Head lice aren't dangerous, just itchy.


"Head Lice." 16 May 2008. Centers for Disease Control and Prevention. CDC. 22 Jun 2008

Hill, N., et al."Single blind, randomised, comparative study of the Bug Buster kit and over the counter pediculicide treatments against head lice in the United Kingdom." BMJ. Aug 2005

Mumcuoglu, K.Y. "Prevention and treatment of head lice in children." Paediatric Drugs. Jul-Sep 1999