Southeastern Idaho Public Health

Head Lice

The Head Louse - What is it?

A head louse, Pediculosis, is an insect that lives on the human scalp and feeds on blood, which causes itching. Head lice are not known to transmit diseases under natural conditions.

Who gets Head Lice and how?

Anyone can get head lice, but they are most common on young school-age children. Personal cleanliness does not prevent a person from getting head lice.

  • Clearing up some common myths:
  • Personal cleanliness will not prevent head lice. Anyone can get them, whether clean or dirty.
  • Head Lice can not jump or fly.
  • Head Lice come from another person, not from dogs, cats, or other pets.
  • Carpets and furniture are not a favorable place for lice. They do not provide the warmth, food, or moisture needed for lice to survive.
  • No solvent (vinegar, etc.) will effectively dissolve the cement that holds nits to the hair.
  • Home remedies are not recommended.
What to look for if Head Lice is suspected:

If your child scratches his or her head frequently or if you hear of head lice occurring on frequent visitors to your home or on close friends of your child, inspect your child's hair for:


These look like tiny oval objects glued to the side of the hair shafts. Their length is less than 1/2 the diameter of the head of a pin.


Lice and nits are most likely to be found near the scalp where the hair is thickest, usually behind the ears and around the nape of the neck. Lice avoid the light. They grow from slightly larger than the nit up to 1/8 inch in length.


Hair casts (material from the hair follicles) may be mistaken for nits. Both may be on the hair at the same time. A hair cast looks like a small collar or ball and slides easily along the hair shaft. Hair casts are unrelated to louse infestation.

How to control Head Lice on the person:
  • A variety of medications containing insecticides to control head lice are available from your drug stores. Or contact your physician for a prescription.
  • Carefully follow all directions on a pediculicide label.
  • Contact your physician for recommended treatment of pregnant women and children under two years of age.
  • Remove as many nits as possible. Specially made fine tooth combs are sometimes helpful in removing nits.
  • Cutting or shaving hair is not necessary.
Control Head Lice on clothing, bed linens, and furniture:

As a rule, only relatively small numbers of head lice will occur away from their normal host, a person. Away from their host, they will usually die in 3 days or less.

Therefore, the following simple control measures are sufficient to prevent reinfestation after treating the infested persons.

  • Vacuum furniture, rugs, and floors.
  • Wash bed linens and washable clothing in hot water (140°F) for 20 minutes.
  • Heat dry clothing or other fabric items in a clothes dryer (hot cycles 155°F) for 20 minutes.
  • Dry clean clothing that cannot be washed or store articles for 20 days in sealed plastic bags.
  • Disinfect combs, brushes, barrettes and similar items by soaking in 150°F water for 20 minutes or soaking in the lice shampoo for one hour.
Signs of an unsuccessful treatment:

New nits will continue to appear on hair next to the scalp.

Some children, seeming free of lice and nits after each complete treatment will have "repeat infestations." This often occurs while others in similar circumstances (for example, same class in school) remain free of lice.

Signs of a successful treatment:

No new nits will be laid. When first laid, nits are attached to hair near the scalp. As the hair grows, they are moved away from the scalp. By 11 days after a successful treatment, no nits will be closer than 1/4 inch from the scalp.

Ways to prevent the spread of Head Lice:
  • Do not use personal items belonging to others. (Combs, hair brushes, towels, hats, clothing, etc.)
  • Avoid hanging hats and coats on the same hook with others' clothing. If individual hooks are not available, personal belonging may be placed in a plastic grocery sack.
  • Learn to recognize signs of head louse infestations and check for them if a child or family member scratches the head often.
  • Treat promptly when head lice are found.
  • Notify others. (School, Teacher, Friends, Parents)
Three Steps to Eliminate Head Lice

Controlling outbreaks of head lice can be accomplished by following three simple steps.

Step 1: Killing the Lice

Parents can purchase a pediculicide to kill the lice. There are a variety of formulations available as over the counter or prescription products. By carefully reading and following the instructions, parents can successfully eradicate the lice. At times, reapplication may be needed.

Step 2: Removing Nits

Although a tedious and time consuming procedure, nit removal is crucial to eradication. After killing the lice, it is extremely important to remove all nits with a special comb usually provided with lice treatment products. Re-infestation can occur very quickly if all nits are not eliminated. Children may not be permitted to go back to school if they have any nits.

The following hints can be used when combing hair to help ensure complete extermination:

  • Using a conditioner or olive oil may make combing smoother, since the comb has very fine teeth which may make the task painful to the child.
  • Working with small sections of hair makes the job easier. Keep the sections to one inch or less.
  • Rinse the comb after each use.
  • Spraying the hair with water mist avoids tangles.
  • Pinning the hair back after it has been combed will help keep track of your progress.
Step 3: Cleaning the Environment

Head lice can survive away from the host for 24 hours and nits have been reported to survive in hot and humid climates for up to 10 days. Yet another reason why it is so important to sanitize the environment.

Head Lice
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Links & Downloads

  How to talk to your kids about Head Lice
  CDC Head Lice FAQs