What are head lice?


Who is at risk for getting head lice?



What do head lice look like?


Actual size of the three lice forms compared to a penny. (CDC Photo)



Illustration of egg on a hair shaft. (CDC Photo)

Illustration of egg on a hair shaft. (CDC Photo)

Nymph form. (CDC Photo)

Nymph form. (CDC Photo)



Adult louse. (CDC Photo)

Adult louse. (CDC Photo)



Adult louse claws. (CDC Photo)

Adult louse claws. (CDC Photo)

Where are head lice most commonly found?

Head lice and head lice nits are found almost exclusively on the scalp, particularly around and behind the ears and near the neckline at the back of the head. Head lice or head lice nits sometimes are found on the eyelashes or eyebrows but this is uncommon. Head lice hold tightly to hair with hook-like claws at the end of each of their six legs. Head lice nits are cemented firmly to the hair shaft and can be difficult to remove even after the nymphs hatch and empty casings remain.


What are the signs and symptoms of head lice infestation?

  • Tickling feeling of something moving in the hair.
  • Itching, caused by an allergic reaction to the bites of the head louse.
  • Irritability and difficulty sleeping; head lice are most active in the dark.
  • Sores on the head caused by scratching. These sores can sometimes become infected with bacteria found on the person’s skin.

How did my child get head lice?


Although uncommon, head lice can be spread by sharing clothing or belongings. This happens when lice crawl, or nits attached to shed hair hatch, and get on the shared clothing or belongings. Examples include:

  • sharing clothing (hats, scarves, coats, sports uniforms) or articles (hair ribbons, barrettes, combs, brushes, towels, stuffed animals) recently worn or used by an infested person;
  • or lying on a bed, couch, pillow, or carpet that has recently been in contact with an infested person.

Dogs, cats, and other pets do not play a role in the spread of head lice.

How is head lice infestation diagnosed?

The diagnosis of a head lice infestation is best made by finding a live nymph or adult louse on the scalp or hair of a person. Because nymphs and adult lice are very small, move quickly, and avoid light, they can be difficult to find. Use of a magnifying lens and a fine-toothed comb may be helpful to find live lice. If crawling lice are not seen, finding nits firmly attached within a ¼ inch of base of the hair shafts strongly suggests, but does not confirm, that a person is infested and should be treated. Nits that are attached more than ¼ inch from the base of the hair shaft are almost always dead or already hatched. Nits are often confused with other things found in the hair such as dandruff, hair spray droplets, and dirt particles. If no live nymphs or adult lice are seen, and the only nits found are more than ¼-inch from the scalp, the infestation is probably old and no longer active and does not need to be treated.

If you are not sure if a person has head lice, the diagnosis should be made by their health care provider, local health department, or other person trained to identify live head lice.

How is head lice infestation treated?

More on: Treatment

Is infestation with head lice reportable to health departments?

Most health departments do not require reporting of head lice infestation. However, it may be beneficial for the sake of others to share information with school nurses, parents of classmates, and others about contact with head lice.

I don’t like my school’s “no-nit” policy; can CDC do something?

No. CDC is not a regulatory agency. School head lice policies often are determined by local school boards. Local health departments may have guidelines that address school head lice policies; check with your local and state health departments to see if they have such recommendations.

More on: Head Lice Information for Schools

Do head lice spread disease?


Can head lice be spread by sharing sports helmets or headphones?


Can wigs or hair pieces spread lice?

Head lice and their eggs (nits) soon perish if separated from their human host. Adult head lice can live only a day or so off the human head without blood for feeding. Nymphs (young head lice) can live only for several hours without feeding on a human. Nits (head lice eggs) generally die within a week away from their human host and cannot hatch at a temperature lower than that close to the human scalp. For these reasons, the risk of transmission of head lice from a wig or other hairpiece is extremely small, particularly if the wig or hairpiece has not been worn within the preceding 48 hours by someone who is actively infested with live head lice.

Can swimming spread lice?


Head lice may be spread by sharing towels or other items that have been in contact with an infested person’s hair, although such spread is uncommon. Children should be taught not to share towels, hair brushes, and similar items either at poolside or in the changing room.

Swimming or washing the hair within 1–2 days after treatment with some head lice medicines might make some treatments less effective. Seek the advice of your health care provider or health department if you have questions.

Source: (https://www.cdc.gov/parasites/lice/head/gen_info/faqs.html) Accessed 07/30/2019
