Head Lice - NYC Health

Health

Promoting and Protecting the City's Health


Health TopicsNeighborhood HealthEmergency Prep


Head Lice

Head lice are found among hair on the human scalp. Commonly, they can be found on the scalp behind the ears and near the neckline at the base of the scalp.

Can you see head lice?

Head lice are 2mm (male) to 3mm (female) in length. Full-grown adults are approximately the size of a sesame seed. The color of head lice tends to match the hair color of human hosts, ranging from pale tan to dark brown.

Can my child go to school with head lice?

There is now a "no head lice" policy for all NYC public schools, but no longer a "no nit" policy. See the NYC Department of Education website for more information.

What are nits?

Head lice lay oval, yellowish-white, opalescent eggs (nits) on the base of the hair shafts. Eggshells can remain attached to the hair long after the young have hatched.

If someone has head lice, does it mean that they or their home is not clean?

No. A common misconception is that lice infestation is a result of poor hygienic practices. In fact, it is actually believed that head lice prefer clean hair to dirty hair. However, their number increases due to a lack of combing and bathing.

How do children (or adults) get head lice?

Head lice infestation usually occurs during prolonged and direct head-to-head contact with a person who has head lice. Head lice may be spread through shared use of combs and hairbrushes, use of bedding by more than one person, and the sharing of hats and other contaminated accessories. Head lice can survive only for brief periods of time on bedding or upholstered furniture. Casual contact, such as occurs in schools, generally does not lead to transfer of head lice.

Can pets get head lice?

No. Head lice feed on blood from their human hosts and die in the absence of a human host (ie. they cannot live on pets). They cannot survive more than 48 hours at room temperature (23-24° C) away from their host.

How can I help my child get rid of head lice?

Consult your physician if you think you or your children have lice. The physician may prescribe a medicated shampoo as a treatment and a schedule of its use.

Comb wet hair with a lice comb (extremely fine-toothed comb available in drug stores) to remove nymphs and adult lice.

Do not use shampoos that contain Lindane. Lindane use is described as hazardous by the Agency for Toxic Substances and Disease registry of the U.S. Department of Health and Health and Human Services. Your physician or a pharmacist may recommend over-the-counter products (pediculicides).

Do not dry your hair with a hair dryer after application of a pediculicide because some treatments contain chemicals that are flammable.

It may be necessary to repeat the treatment 7-10 days after the first application.

In addition to the treatment of an infested child or adult:

All bedding, towels, and clothing from the infested individual should be cleaned with soap and hot water and placed in a dryer for at least 20 minutes to help kill any remaining lice.

Dry-clean all clothes that need to be dry-cleaned.

Seal the infested individual's stuffed toys in a plastic bag and leave them for 10 days to allow all lice to die of starvation.

Dispose of or soak combs and hairbrushes in rubbing alcohol or the medicated shampoo used to kill lice.

Throw out any hair accessories, such as hair elastics and ribbons.

Thoroughly vacuum carpets and upholstered furniture. Pets cannot become infested with head and body lice, so no precaution is required.

Resources

Head lice information for parents from KidsHealth (including Spanish translation)