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Head Lice: Facts and Details

What are head lice?

Head lice are parasitic insects found on the heads of people. Head lice are not known to spread disease.

How common are head lice?

Head lice is common in the United States, where an estimated six to 12 million infestations occur each year in children ages three to 11 years.

What are the signs and symptoms of head lice?

Symptoms of head lice infestation may include a tickling feeling in the hair, itching caused by an allergic reaction to the bites, irritability, and sores on the head caused by scratching. These sores can sometimes become infected.

How do people become infested?

Head lice are spread by contact with an already infested per-son. Contact is common through slumber parties, sports activities, camps, and the playground. Wearing infested clothing (e.g., hats, scarves); using infested combs, brushes or towels; or lying on items that have recently been in contact with an infest-ed person (e.g., bed, pillows) can also spread head lice.

What do head lice look like?


Nits are lice eggs. They are very small (about the size of a knot in thread), yellow to white, oval, hard to see, and are often confused for dandruff or hairspray droplets. Nits are laid by the adult female at the base of the hair shaft (within 1/4 inch of the scalp) and are firmly attached to the hair shaft. Nits take about eight to nine days to hatch.


The nit hatches into a baby louse called a nymph. It looks like an adult head louse, but is smaller. Nymphs mature into adults about nine to 12 days after hatching.


The adult louse is about the size of a sesame seed, has six legs, and is tan to grayish-white. In persons with dark hair, the adult louse will look darker. Adult lice can live up to 30 days on a person’s head. To live, adult lice need to feed on blood. If the louse falls off a person, it dies within two days.

Who is at risk for head lice?

Anyone can get head lice, but infestations are most common among preschool children attending childcare, elementary school children, and the household members of infested children. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice.

How are head lice treated?

The most important step in treating head lice infestation is to treat the person and other family members with medication to kill the lice. This medication may be by prescription or over-the-counter. Wash clothing and bedding worn or used by the infest-ed person in the 2 day period before treatment is started.

The American Academy of Pediatrics (AAP) no longer recommends the use of no-nit policies in schools. The current recommendation is that a child found to have head lice can finish the school day and return to school once they begin treatment. School districts in Kansas set their own head lice policies.

How can you prevent head lice?

Head lice do not survive long if they fall off a person and cannot feed. The following steps can help you avoid re-infestation: