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Head Lice

How to treat head lice



Louse seen from above.

Source: CDC/Dr. Dennis D. Juranek (CDC Public Health Image Library)

  • Anyone who has hair can get head lice. They are not caused by being dirty.
  • Head lice don’t spread illness or disease.
  • Head lice are spread mainly by touching heads with someone who has head lice. They can sometimes be spread by sharing items such as hats, hairbrushes, and combs that were used by someone who has head lice.
  • If 1 person in the family has lice, then someone else likely does too. It is important to check everyone in the family.
  • It’s a good idea to check younger, school-aged children for head lice every week.
  • These tiny insects can cause a lot of stress and create a lot of work.

About head lice

Head lice are tiny insects that can be the size of a head of a pin up to about the size of a sesame seed (seeds found on a hamburger bun). They can be tan, brown, dark grey, or greyish-white.

Head lice crawl very quickly, which can make them hard to see. They don’t jump, fly, or swim.

Head lice live only on the human head and can make the scalp (the skin on the top of your head) itchy. They don't spread illness or disease. They can be found anywhere on the head, but especially behind the ears and the neck area at the base of the scalp. They don’t live on and aren’t spread by pets.

Adult head lice lay about 8 eggs (called nits) every day. The nits are stuck to the hair near the scalp. Nits are hard to see and can sometimes be mistaken for dandruff or hairspray droplets. After the nits hatch, their empty shell stays stuck to the hair.

You can’t get rid of lice with a hair brush or with a hair dryer.

Life cycle

It’s important to understand the life cycle of head lice to understand the treatment schedule for head lice.

  • Only adult lice lay nits (eggs).
  • Nits take between 7 and 10 days to hatch.
  • The lice become adults 6 to 10 days after they’ve hatched.
Life cycle of head lice. 

Detection combing​

Detection combing is an organized way to look for lice and nits in the hair, from the scalp​ outwards. If you only part the hair and look at the scalp, you may miss seeing lice or nits.

Adult using a lice detection comb on a child's head

To do detection combing, you need:

  • A fine-toothed comb or head lice detection comb. You can buy these in most drug stores.
  • A regular comb.
  • White tissue or paper towel.
  • A sink or a bowl of warm water.
  • Good lighting (daylight is best).


  1. Wash the hair well, dry it with a towel, then comb with a regular comb. The hair should be damp so it doesn’t become “fly away,” which can make it harder for the lice or nits to stick to the comb.
  2. Change to the fine-toothed comb. Starting on one side of the head, use your fingers to part the hair. Place the comb at the top of the head, with the teeth touching the skin of the scalp. Keeping the comb in contact with the scalp for as long as possible, slowly pull the comb towards the end of the hair. For long or thick hair, it might be helpful to clip the hair in several sections and thoroughly comb through 1 section at a time.
  3. Look closely at the teeth of the comb. Wipe the fine-toothed comb on white tissue or paper towel after each stroke. Look on the tissue and the comb to see if there are any live lice. A magnifying glass may help.
  4. Rinse the comb in a sink or bowl of warm water after every stroke, then wipe dry.
  5. Comb over and over again from the top of the head to the ends of the hair in all directions, until you’ve worked around the entire head. It should take 10 to 15 minutes, depending how long the hair is.
  6. When you’re done, clean the combs and clips well under running water. Put the tissue you used to clean the combs in the garbage right away. If you find any lice or nits, soak the combs and clips in hot water to clean them (see below for more information on washing items).

How do I know if I need to treat my child?

If you do 1 detection comb and don’t find nits or any live lice, you don’t have to check again until your next regular weekly check.

If you do detection combing and you:

Find any lice Find only nits (eggs)
  • treat hair with an approved product
  • keep detection combing every 3 to 4 days for 12 days
  • If you find any live lice, treat the hair.
  • If you don't find anything after 12 days, don't treat the hair.

If you find something in the hair while combing and aren’t sure what it is, stick it on a piece of paper or clear sticky tape and show it to your healthcare provider. There may be other things in the hair that aren’t lice.

Treating head lice

You only need to treat hair when you find live head lice. You do not need to treat the hair if you find only nits. If you have questions, ask your pharmacist.

Head lice shampoos, cream rinses, and sprays have been tested and are safe and effective treatments for head lice. You can buy them at any pharmacy and don’t need a prescription. If you’re not sure which one is best for your needs, talk to your pharmacist.

Read and follow the directions on the head lice shampoo, cream rinse, or spray. For the treatment to work, you must follow the instructions exactly, including if the hair has to be wet or dry, and when to treat a second time.

You may have to buy more of the same product if you have to use it on longer hair. It’s important to use the correct amount of product each time. Using less of the product to make it go further will mean that the lice survive and more treatments will be needed.

The shampoo, cream rinse, or spray kills the live lice on the head but may not kill the nits.

While the nits don’t need to be removed from the hair, some people use a comb to remove nits after using lice treatment because they don’t like the look of nits in the hair.

A second treatment with head lice shampoo, cream rinse, or spray is almost always needed 7 to 10 days after the first treatment to kill newly hatched lice. If you’re not sure if a second treatment is needed, talk to your pharmacist.

Washing items

Wash any items that were in contact with the head of the person who has lice, like combs, brushes, bedding, or hats. This includes the combs you used for detection combing.

  • Washable items can be machine washed, soaked in hot water, or placed in the dryer on hot heat.
  • Put non-washable items in a sealed plastic bag for 2 weeks. Lice can’t live this long away from the human head, so this will kill the lice.

How can I learn more?

To learn more about head lice, watch head lice (video). You can also:

  • talk to your pharmacist or family doctor
  • visit your public health office
  • call Health Link at 811​

Current as of: July 25, 2023

Author: Public Health, Alberta Health Services