Frequently Asked Questions

About Head Lice

What are head lice?

Head lice are tiny insects that live close to the scalp and feed on human blood. Head lice are found most often on the back of the neck and behind the ears.

How do head lice spread?

Although lice can’t jump or fly, they can spread very easily from person to person through close contact or through shared clothing or personal items (such as a hat, towel, or hairbrush).

How common is head lice?

Although the thought of having a child with head lice can leave you feeling anxious, know that head lice is both extremely common and very easy to treat. Head lice are found worldwide, predominantly in preschool and elementary school-age children. An estimated 6 to 12 million infestations of lice occur each year in the United States alone.

How can I identify head lice?

To understand how to identify lice, it helps to know the three different forms of head lice:

Eggs (nits): Nits are oval-shaped lice eggs that attach themselves to the hair shaft. They are hard to see with the naked eye, as they’re only about as large as a knot in a piece of thread. Usually white or yellow in color, they are often confused with dandruff or scabs. Nits usually take about 8-9 days to hatch. Eggs that are likely to hatch are usually located very close to the base of the hair shaft.

Nymph: A nymph is an immature louse (singular of lice) that hatches from the nit. It takes about 9-12 days for a nymph to mature into an adult.

Adult louse: An adult louse is about the size of a sesame seed, has six legs, and is tan to grayish-white in color. An adult louse, which must feed on blood in order to live, can survive up to 30 days on a person’s head but will die within one or two days if it falls off a person.

The most common symptom associated with head lice is itching, although it may take some time for symptoms to develop.

Head lice can usually be detected by looking closely for live lice or eggs in the hair. Use of a magnifying glass can assist in the search. If you’re not sure whether your child has head lice, ask a school nurse or other health care provider to conduct a thorough search.

How long can lice survive if they fall off a person?

Head lice survive less than 1-2 days if they fall off a person and cannot feed. Nits usually die within a week if they are not kept at the same temperature as that found close to the human scalp.

Does poor hygiene cause head lice?

Some people think that only “dirty kids” get head lice. This is simply not true. Lice are attracted to blood, not to dirty hair. Personal hygiene or cleanliness in the home has nothing to do with getting head lice.

Can pets cause lice to spread?

Dogs, cats, and other pets do not spread lice. Lice pass from person to person through close contact with the hair or personal items of a person with head lice.

Do head lice spread disease?

Although head lice can cause symptoms such as itching or scalp sores, they have not been shown to spread disease. They are thought to be more a nuisance than a health hazard.

Will swimming kill head lice?

Head lice can hold tightly to human hair, even when submerged under water. Chlorine found in pool water does not kill head lice.

Can lice jump from person to person?

Lice cannot jump or fly. They can only crawl. They pass from person to person only through contact, either directly or through the exchange of a personal item such as a brush, comb, or hat.

Once head lice are killed, is the problem solved?

The louse itself is not the only problem for someone with head lice. The eggs of a louse, also called nits, must also be killed. Nits will hatch after about 7-10 days and must be removed. Using a product such as Nix® Crème Rinse, which provides a residue for up to 14 days, can help eliminate the newly hatched nits.

About Head Lice Treatment and Prevention

How can I prevent my child from getting lice?

Some tips to protect your child from getting head lice include: avoiding direct head-to-head contact with others; not sharing clothing or personal items; separating clothing; and cleaning items that have come into contact with a person infested with head lice in hot water (130° F) and then drying the items in the dryer on a high heat setting.

Should I shave my child’s head?

Many would consider this approach to be overkill. While shaving your child’s head can help solve the problem, it’s a drastic and unnecessary move since so many effective treatments such as Nix® Lice Treatment products are available.

I’ve heard that Nix® Lice Treatment products leave a residual film on the hair and that this is causing lice to build up a resistance.

In truth, all pediculicide (lice-killing) products available today are susceptible to resistance. Nix® does have a residual effect. This means that some residual or lingering activity of Nix® remains on the hair for up to two weeks, even with regular shampooing. This residual activity allows Nix® to kill lice—including baby lice as they hatch—and protect against lice reinfestation for up to 14 days. Products with longer residual effects tend to be more effective in killing lice eggs.1

Reference: 1. Mazurek CM, Lee NP. How to manage head lice. West J Med. 2000 May; 172(5): 342–345.