5 Steps for Proper Head Lice Treatment

Identify Head Lice

Head lice nit (egg)
Nits are shaped like a teardrop and attached to the hair follicle. Image © Melanie Martinez

Head lice treatment starts with identifying an infestation. Head lice are parasites that live on human blood. They crawl around on the scalp, eating blood and reproducing, laying eggs (called "nits") on hair follicles.

Live head lice grow to be about the size of a grain of rice, are dark-colored and like to scurry around a lot. The best way to tell if a person is actively infested with head lice is to find the little buggers hard at work. To find live head lice, separate the hair all the way down to the scalp and look for movement.

Unfortunately, head lice don't want to be seen, which would not be good for long-term survival. A second, less accurate way to identify head lice infestation is to look for the nits attached to the hair. Nits are shaped like teardrops and are lighter in color than the live lice. They don't come off the hair easily, which is one way to tell the difference between nits and dandruff.

Head lice lay their eggs on the hair follicle as close to the scalp as possible. It's the warmth of the scalp that keeps the nits alive, which means if the nits have not hatched by the time the hair grows more than half an inch, they probably won't hatch at all.

Head Lice Treatment

Only active infestations need to be treated. If nits are found on hair within half an inch of the scalp, it may be an active infestation. If live head lice are found bustling about on the scalp, it is definitely an active infestation. If no live head lice are seen and the only nits are more than half an inch from the scalp, it's likely not an active infestation and no treatment is necessary.

Head lice are typically treated with a pediculicide (lice-killing) shampoo. There are two over-the-counter shampoos available: Permethrin and Pyrethrins, with piperonyl butoxide. If over-the-counter treatments don't work, there are prescription medications available through your doctor as well: Malathion and Lindane.

Prepare the Hair

Separate hair to treat for lice
Divide long hair into sections to adequately cover with lice shampoo. Image © Melanie Martinez

When using lice shampoo, be sure to follow the manufacturer's directions. With that in mind, here are some general tips to get the most success out of each treatment.

The trick with lice shampoo is to get it on the scalp. Live head lice don't travel too far away from the warmth of the skin so getting as close as possible makes all the difference. To prepare the hair for lice shampoo, follow these steps:

  1. Wash the hair but do not use conditioner or combination shampoo/conditioner.
  2. According to the directions of the product you are using, dry the hair if necessary. Usually, Pyrethrins with piperonyl butoxide is applied to dry hair and Permethrin is applied to wet hair.
  3. Comb hair out to get rid of knots.
  4. Put a towel around the person's shoulders to protect her or him from the lice-killing shampoo.
  5. Divide the hair into sections, so you can easily reach the scalp.

This technique works for head lice shampoos as well as gels.

It's not mandatory to wear gloves with over-the-counter lice shampoos, but it wouldn't hurt. If you are using a prescription shampoo, absolutely wear gloves. These are powerful chemicals that can cause reactions very similar to pesticides. If any lice shampoos are accidentally ingested, call 911 immediately.

Apply Lice Shampoo or Gel

Apply lice shampoo
Apply lice shampoo as close to the scalp as possible. Image © Melanie Martinez

Apply lice shampoos as close to the scalp as possible. The chemicals in the shampoo are there to kill live head lice and sometimes nits. Coating the hair all the way to the tips is not necessary. For long hair, you'll waste a lot of product where it's not needed.

Focus on warmer areas where head lice like to live: especially the neckline, behind the ears and anywhere you find big collections of nits.

These chemicals can be absorbed through the skin, so follow the manufacturer's directions. For example, keeping the chemicals in your hair longer than the directions is not better: if the directions say to wash the product off after 10 minutes, don't wait until 15 or 20 minutes to get a better result.

Remove Nits

Comb nits out with fine-tooth comb
Use a nit comb or flea/tick comb to remove nits. Image © Melanie Martinez

Once the head lice shampoo is washed out, use a nit comb (usually included with the shampoo or lotion) to remove nits. Combs work well but be diligent. It often takes work to remove nits, and the comb doesn't always do it. You may have to pick out nits with a fingernail.

After treatment with lice-killing shampoo, you'll have to keep removing nits as you find them. Most of the shampoos only kill live head lice and leave the nits to hatch. Both of the over-the-counter products recommend retreatment after the nits have hatched and before the new lice get old enough to lay more eggs. Retreatment after using prescription lice shampoo may or may not be necessary.

Prevent Reinfestation

Clean tools after use
Soak combs and brushes in hot water (more 130 degrees) for at least 5 minutes. Image © Melanie Martinez

After head lice treatment, soak all combs and brushes used on the infested hair in hot water (over 130 degrees) for at least 5 minutes.

Prevent Reinfestation

Head lice don't live long away from the heat of the scalp. Carefully cleaning the areas where an infested person may have sat or slept is probably good enough. Indeed, the CDC's recommendations on the subject are a little confusing.

For instance, you only have to worry about bedding or clothing used by the infested person in the last 48 hours, but then you must bag it for 2 weeks. So is it safe to use bedding and clothing 2 weeks or 2 days after an infested person? I don't really have an answer for you. I suggest doing your best to clean bedding, clothing and carpeting used by infested folks, but don't worry too much about it.

To be safe:

  • Wash any bedding or clothing used by an infested person within the last 2 days in hot water (130 degrees or more). 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.
  • Vacuum carpets and furniture as well as you can.
  • Stay away from spray fumigation products; they can be toxic, and they aren't necessary.

Again, don't worry too much. Live head lice can't live more than a day or two away from the warmth of the scalp, and nits will die within a week. Stuffed animals or other items that can't be washed can be put in a plastic bag for 2 weeks to make sure all head lice and nits are dead.


"Head Lice." Centers for Disease Control and Prevention. CDC. 2008.

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