Adult head lice are roughly 2–3 mm long. Head lice infest the head and neck and attach their eggs to the base of the hair shaft. Lice move by crawling; they cannot hop or fly.

Head lice infestation, or pediculosis, is spread most commonly by close person-to-person contact. Dogs, cats, and other pets do not play a role in the transmission of human lice.

Both over-the-counter and prescription medications are available for treatment of head lice infestations.

What are head lice?

Head lice are tiny insects that live on people's heads. Adult lice are about the size of sesame seeds. The eggs, called nits, are even smaller - about the size of a dandruff flake. Lice and nits are found on or near the scalp, most often at the neckline and behind the ears.

Head lice are parasites, and they need to feed on human blood to survive. They are one of the three types of lice that live on humans. The other two types are body lice and pubic lice. Each type of lice is different, and getting one type does not mean that you will get another type.

How do head lice spread?

Lice move by crawling, because they cannot hop or fly. They spread by close person-to-person contact. Rarely, they can spread through sharing personal belongings such as hats or hairbrushes. Personal hygiene and cleanliness have nothing to do with getting head lice. You also cannot get pubic lice from animals. Head lice do not spread disease.

Who is at risk for head lice?

Children ages 3-11 and their families get head lice most often. This is because young children often have head-to-head contact while playing together.

What are the symptoms of head lice?

The symptoms of head lice include

• Tickling feeling in the hair
• Frequent itching, which is caused by an allergic reaction to the bites
• Sores from scratching. Sometimes the sores can become infected with bacteria.
• Trouble sleeping, because head lice are most active in the dark

How do you know if you have head lice?

A diagnosis of head lice usually comes from seeing a louse or nit. Because they are very small and move quickly, you may need to use a magnifying lens and a fine-toothed comb to find lice or nits.

What are the treatments for head lice?

Treatments for head lice include both over-the-counter and prescription shampoos, creams, and lotions. If you want to use an over-the-counter treatment and you aren't sure which one to use or how to use one, ask your health care provider or pharmacist. You should also check with your health care provider first if you are pregnant or nursing, or if you want to use a treatment on a young child.

Follow these steps when using a head lice treatment:

• Apply the product according to the instructions. Only apply it to the scalp and the hair attached to the scalp. You should not use it on other body hair.
• Use only one product at a time, unless your health care provider tells you to use two different kinds at once
• Pay attention to what the instructions say about how long you should leave the medicine on the hair and on how you should rinse it out
• After rinsing, use a fine-toothed comb or special "nit comb" to remove dead lice and nits
• After each treatment, check your hair for lice and nits. You should comb your hair to remove nits and lice every 2-3 days. Do this for 2-3 weeks to be sure that all lice and nits are gone.

All household members and other close contacts should be checked and treated if necessary. If an over-the-counter treatment does not work for you, you can ask your health care provider for a prescription product.

Can head lice be prevented?

There are steps you can take to prevent the spread of lice. If you already have lice, besides treatment, you should

• Wash your clothes, bedding, and towels with hot water, and dry them using the hot cycle of the dryer
• Soak your combs and brushes in hot water for 5-10 minutes
• Vacuum the floor and furniture, particularly where you sat or lay
• If there are items that you cannot wash, seal them in a plastic bag for two weeks

To prevent your children from spreading lice:

• Teach children to avoid head-to-head contact during play and other activities
• Teach children not to share clothing and other items that they put on their head, such as headphones, hair ties, and helmets
• If your child has lice, be sure to check the policies at school and/or daycare. Your child may not be able to go back until the lice have been completely treated.

There is no clear scientific evidence that lice can be suffocated by home remedies, such as mayonnaise, olive oil, or similar substances. You also should not use kerosene or gasoline; they are dangerous and flammable.

What are head lice?

The head louse, or Pediculus humanus capitis, is a parasitic insect that can be found on the head, eyebrows, and eyelashes of people. Head lice feed on human blood several times a day and live close to the human scalp. Head lice are not known to spread disease.

Who is at risk for getting head lice?

Head lice are found worldwide. In the United States, infestation with head lice is most common among pre-school children attending child care, elementary schoolchildren, and the household members of infested children. Although reliable data on how many people in the United States get head lice each year are not available, an estimated 6 million to 12 million infestations occur each year in the United States among children 3 to 11 years of age. In the United States, infestation with head lice is much less common among African-Americans than among persons of other races, possibly because the claws of the head louse found most frequently in the United States are better adapted for grasping the shape and width of the hair shaft of other races.

Head lice move by crawling; they cannot hop or fly. Head lice are spread by direct contact with the hair of an infested person. Anyone who comes in head-to-head contact with someone who already has head lice is at greatest risk. Spread by contact with clothing (such as hats, scarves, coats) or other personal items (such as combs, brushes, or towels) used by an infested person is uncommon. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice.

What do head lice look like?

Head lice have three forms: the egg (also called a nit), the nymph, and the adult.

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?

Head-to-head contact with an already infested person is the most common way to get head lice. Head-to-head contact is common during play at school, at home, and elsewhere (sports activities, playground, slumber parties, camp).

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.

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.

Do head lice spread disease?

Head lice should not be considered as a medical or public health hazard. Head lice are not known to spread disease. Head lice can be an annoyance because their presence may cause itching and loss of sleep. Sometimes the itching can lead to excessive scratching that can sometimes increase the chance of a secondary skin infection.

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

Head lice are spread most commonly by direct contact with the hair of an infested person. Spread by contact with inanimate objects and personal belongings may occur but is very uncommon. Head lice feet are specially adapted for holding onto human hair. Head lice would have difficulty attaching firmly to smooth or slippery surfaces like plastic, metal, polished synthetic leathers, and other similar materials.

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?

Data show that head lice can survive under water for several hours but are unlikely to be spread by the water in a swimming pool. Head lice have been seen to hold tightly to human hair and not let go when submerged under water. Chlorine levels found in pool water do not kill head 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.

In the United States, infestation with head lice (Pediculus humanus capitis) is most common among preschool- and elementary school-age children and their household members and caretakers. Head lice are not known to transmit disease; however, secondary bacterial infection of the skin resulting from scratching can occur with any lice infestation.

Getting head lice is not related to cleanliness of the person or his or her environment.

Head lice are mainly spread by direct contact with the hair of an infested person. The most common way to get head lice is by head-to-head contact with a person who already has head lice. Such contact can be common among children during play at

• School,
• Home, and
• Elsewhere (e.g., sports activities, playgrounds, camp, and slumber parties).

Uncommonly, transmission may occur by

• Wearing clothing, such as hats, scarves, coats, sports uniforms, or hair ribbons worn by an infested person;
• Using infested combs, brushes or towels; or
• Lying on a bed, couch, pillow, carpet, or stuffed animal that has recently been in contact with an infested person.

Reliable data on how many people get head lice each year in the United States are not available; however, an estimated 6 million to 12 million infestations occur each year in the United States among children 3 to 11 years of age. Some studies suggest that girls get head lice more often than boys, probably due to more frequent head-to-head contact.

In the United States, infestation with head lice is much less common among African-Americans than among persons of other races. The head louse found most frequently in the United States may have claws that are better adapted for grasping the shape and width of some types of hair but not others.

Head lice are not known to transmit any disease and therefore are not considered a health hazard.

Head lice infestations can be asymptomatic, particularly with a first infestation or when an infestation is light. Itching (“pruritus”) is the most common symptom of head lice infestation and is caused by an allergic reaction to louse bites. It may take 4–6 weeks for itching to appear the first time a person has head lice.

Other symptoms may include the following:

• A tickling feeling or a sensation of something moving in the hair
• Irritability and sleeplessness
• Sores on the head caused by scratching, which can sometimes become infected with bacteria normally found on a person’s skin.

Misdiagnosis of head lice infestation is common. The diagnosis of head lice infestation is best made by finding a live nymph or adult louse on the scalp or hair of a person.

Because adult and nymph lice are very small, move quickly, and avoid light, they may be difficult to find. Use of a fine-toothed louse comb may facilitate identification of live lice.

If crawling lice are not seen, finding nits attached firmly within ¼ inch of the base of hair shafts suggests, but does not confirm, the person is infested. Nits frequently are seen on hair behind the ears and near the back of the neck. Nits that are attached more than ¼ inch from the base of the hair shaft are almost always non-viable (hatched or dead). Head lice and nits can be visible with the naked eye, although use of a magnifying lens may be necessary to find crawling lice or to identify a developing nymph inside a viable nit. Nits are often confused with other particles found in hair such as dandruff, hair spray droplets, and dirt particles.

If no nymphs or adults are seen, and the only nits found are more than ¼ inch from the scalp, then the infestation is probably old and no longer active — and does not need to be treated.

Treatment for head lice is recommended for persons diagnosed with an active infestation. All household members and other close contacts should be checked; those persons with evidence of an active infestation should be treated. Some experts believe prophylactic treatment is prudent for persons who share the same bed with actively-infested individuals. All infested persons (household members and close contacts) and their bedmates should be treated at the same time.

Some pediculicides (medicines that kill lice) have an ovicidal effect (kill eggs). For pediculicides that are only weakly ovicidal or not ovicidal, routine retreatment is recommended. For those that are more strongly ovicidal, retreatment is recommended only if live (crawling) lice are still present several days after treatment. To be most effective, retreatment should occur after all eggs have hatched but before new eggs are produced.

When treating head lice, supplemental measures can be combined with recommended medicine (pharmacologic treatment); however, such additional (non-pharmacologic) measures generally are not required to eliminate a head lice infestation. For example, hats, scarves, pillow cases, bedding, clothing, and towels worn or used by the infested person in the 2-day period just before treatment is started can be machine washed and dried using the hot water and hot air cycles because lice and eggs are killed by exposure for 5 minutes to temperatures greater than 53.5°C (128.3°F). Items that cannot be laundered may be dry-cleaned or sealed in a plastic bag for two weeks. Items such as hats, grooming aids, and towels that come in contact with the hair of an infested person should not be shared. Vacuuming furniture and floors can remove an infested person's hairs that might have viable nits attached.

Treat the infested person(s):

Requires using an Over-the-counter (OTC) or prescription medication. Follow these treatment steps:

1. Before applying treatment, it may be helpful to remove clothing that can become wet or stained during treatment.
2. Apply lice medicine, also called pediculicide, according to the instructions contained in the box or printed on the label. If the infested person has very long hair (longer than shoulder length), it may be necessary to use a second bottle. Pay special attention to instructions on the label or in the box regarding how long the medication should be left on the hair and how it should be washed out.

   WARNING: Do not use a combination shampoo/conditioner, or conditioner before using lice medicine. Do not re–wash the hair for 1–2 days after the lice medicine is removed.

• Have the infested person put on clean clothing after treatment.
• If a few live lice are still found 8–12 hours after treatment, but are moving more slowly than before, do not retreat. The medicine may take longer to kill all the lice. Comb dead and any remaining live lice out of the hair using a fine–toothed nit comb.
• If, after 8–12 hours of treatment, no dead lice are found and lice seem as active as before, the medicine may not be working. Do not retreat until speaking with your health care provider; a different pediculicide may be necessary. If your health care provider recommends a different pediculicide, carefully follow the treatment instructions contained in the box or printed on the label.
• Nit (head lice egg) combs, often found in lice medicine packages, should be used to comb nits and lice from the hair shaft. Many flea combs made for cats and dogs are also effective.
• After each treatment, checking the hair and combing with a nit comb to remove nits and lice every 2–3 days may decrease the chance of self–reinfestation. Continue to check for 2–3 weeks to be sure all lice and nits are gone. Nit removal is not needed when treating with spinosad topical suspension.
• Retreatment is meant to kill any surviving hatched lice before they produce new eggs. For some drugs, retreatment is recommended routinely about a week after the first treatment (7–9 days, depending on the drug) and for others only if crawling lice are seen during this period. Retreatment with lindane shampoo is not recommended.

Supplemental Measures: Head lice do not survive long if they fall off a person and cannot feed. You don't need to spend a lot of time or money on housecleaning activities. Follow these steps to help avoid re–infestation by lice that have recently fallen off the hair or crawled onto clothing or furniture.

1. Machine wash and dry clothing, bed linens, and other items that the infested person wore or used during the 2 days before treatment using the hot water (130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry–cleaned

   OR

   sealed in a plastic bag and stored for 2 weeks.

2. Soak combs and brushes in hot water (at least 130°F) for 5–10 minutes.
3. Vacuum the floor and furniture, particularly where the infested person sat or lay. However, the risk of getting infested by a louse that has fallen onto a rug or carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. Spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice or nits that may have fallen off the head or crawled onto furniture or clothing.
4. Do not use fumigant sprays; they can be toxic if inhaled or absorbed through the skin.

Prevent Reinfestation

Over-the-counter Medications

Many head lice medications are available “Over-the-counter” without a prescription at a local drug store or pharmacy. Each Over-the-counter product approved by the FDA for the treatment of head lice contains one of the following active ingredients. Always follow the label instructions when administering these medications. If crawling lice are still seen after a full course of treatment contact your health care provider.

1. Pyrethrins combined with piperonyl butoxide;
   Brand name products:
   A–200*, Pronto*, R&C*, Rid*, Triple X*. Pyrethrins are naturally occurring pyrethroid extracts from the chrysanthemum flower. Pyrethrins are safe and effective when used as directed. Pyrethrins can only kill live lice, not unhatched eggs (nits). A second treatment is recommended 9 to 10 days after the first treatment to kill any newly hatched lice before they can produce new eggs. Pyrethrins generally should not be used by persons who are allergic to chrysanthemums or ragweed. Pyrethrin is approved for use on children 2 years of age and older. The efficacy of pyrethrins may be reduced because of development of resistance, but the prevalence of resistance has not been well studied and is unknown. If crawling lice are still seen after a full course of treatment contact your health care provider.
2. Permethrin lotion, 1%;
   Brand name product:
   Nix*. Permethrin is a synthetic pyrethroid similar to naturally occurring pyrethrins. Permethrin lotion 1% is approved by the FDA for the treatment of head lice. Permethrin is safe and effective when used as directed. Permethrin kills live lice but not unhatched eggs. Permethrin may continue to kill newly hatched lice for several days after treatment. A second treatment often is necessary on day 9 to kill any newly hatched lice before they can produce new eggs. Permethrin is approved for use on children 2 months of age and older.Resistance to 1% permethrin has been reported, but its prevalence is unknown. If crawling lice are still seen after a full course of treatment contact your health care provider.

Prescription Medications

The following medications, in alphabetical order, approved by the U.S. Food and Drug Administration (FDA) for the treatment of head lice are available only by prescription. Always follow the instructions of your health care provider when administering these medications. If crawling lice are still seen after a full course of treatment, contact your health care provider.

• Benzyl alcohol lotion, 5%;
  Brand name product: Ulesfia lotion
  *Benzyl alcohol is an aromatic alcohol. Benzyl alcohol lotion, 5% has been approved by the FDA for the treatment of head lice and is considered safe and effective when used as directed. It kills lice but it is not ovicidal. A second treatment is needed 7 days after the first treatment to kill any newly hatched lice before they can produce new eggs. Benzyl alcohol lotion is intended for use on persons who are 6 months of age and older and its safety in persons aged more 60 years has not been established. It can be irritating to the skin.
• Ivermectin lotion, 0.5%;
  Brand name product: Sklice
  *Ivermectin lotion, 0.5% was approved by the FDA in 2012 for treatment of head lice in persons 6 months of age and older. It is not ovicidal, but appears to prevent nymphs (newly hatched lice) from surviving. It is effective in most patients when given as a single application on dry hair without nit combing. It should not be used for retreatment without talking to a healthcare provider.Given as a tablet in mass drug administrations, oral ivermectin has been used extensively and safely for over two decades in many countries to treat filarial worm infections. Although not FDA-approved for the treatment of lice, ivermectin tablets given in a single oral dose of 200 micrograms/kg or 400 micrograms/kg repeated in 9-10 days has been shown effective against head lice. It should not be used in children weighing less than 15 kg or in pregnant women.
• Malathion lotion, 0.5%;
  Brand name product: Ovide
  *Malathion is an organophosphate. The formulation of malathion approved in the United States for the treatment of head lice is a lotion that is safe and effective when used as directed. Malathion is pediculicidal (kills live lice) and partially ovicidal (kills some lice eggs). A second treatment is recommended if live lice still are present 7–9 days after treatment. Malathion is intended for use on persons 6 years of age and older. Malathion can be irritating to the skin. Malathion lotion is flammable; do not smoke or use electrical heat sources, including hair dryers, curlers, and curling or flat irons, when applying malathion lotion and while the hair is wet.
• Spinosad 0.9% topical suspension;
  Brand name product: Natroba
  *Spinosad is derived from soil bacteria. Spinosad topical suspension, 0.9%, was approved by the FDA in 2011. Since it kills live lice as well as unhatched eggs, retreatment is usually not needed. Nit combing is not required. Spinosad topical suspension is approved for the treatment of children 6 months of age and older. It is safe and effective when used as directed. Repeat treatment should be given only if live (crawling) lice are seen 7 days after the first treatment.

For second–line treatment only:

• Lindane shampoo 1%;
  Brand name products: None available
  Lindane is an organochloride. The American Academy of Pediatrics (AAP) no longer recommends it as a pediculicide. Although lindane shampoo 1% is approved by the FDA for the treatment of head lice, it is not recommended as a first–line treatment. Overuse, misuse, or accidentally swallowing lindane can be toxic to the brain and other parts of the nervous system; its use should be restricted to patients for whom prior treatments have failed or who cannot tolerate other medications that pose less risk. Lindane should not be used to treat premature infants, persons with HIV, a seizure disorder, women who are pregnant or breast–feeding, persons who have very irritated skin or sores where the lindane will be applied, infants, children, the elderly, and persons who weigh less than 110 pounds. Retreatment should be avoided.

When treating head lice

1. Do not use extra amounts of any lice medication unless instructed to do so by your physician and pharmacist. The drugs used to treat lice are insecticides and can be dangerous if they are misused or overused.
2. All the medications listed above should be kept out of the eyes. If they get onto the eyes, they should be immediately flushed away.
3. Do not treat an infested person more than 2–3 times with the same medication if it does not seem to be working. This may be caused by using the medicine incorrectly or by resistance to the medicine. Always seek the advice of your health care provider if this should happen. He/she may recommend an alternative medication.
4. Do not use different head lice drugs at the same time unless instructed to do so by your physician and pharmacist.
5. The AAP recommends rinsing all topical pediculicides from the hair over a sink, rather than in the shower or bath to limit skin exposure, and to use warm water rather than hot water to minimize absorption.

Head lice affect millions of children every year. Schoolchildren are commonly affected by head lice, which attach to hair and feed on human blood.

“Although head lice are a year-round problem, the number of cases usually peaks during back-to-school time in the fall and again in January,” says Patricia Brown, M.D., a dermatologist at the U.S. Food and Drug Administration.

Here are some tips to protect your children and your family from this menace.

Who Is at Risk for Getting Head Lice

No matter how good your personal hygiene or how well you clean your home, you can get head lice (Pediculus humanus capitis).

The most common way to get head lice is direct contact with someone who has head lice. Children who spend a lot of time together in close quarters, such as playing or during sports activities, are at risk. Because children play so closely together and often in large groups, lice can easily travel from child to child, especially when they touch heads while playing or talking.

The Centers for Disease Control and Prevention estimate that 6 million to 12 million cases of head lice occur each year in the U.S. in children ages 3 to 11. Head lice cases are most common among children attending childcare or school, and the household members of children with head lice.

Head lice do not live on animals, and you cannot get head lice from your pets. Head lice feed only on humans.

Identifying and Treating Head Lice

Head lice are blood-sucking insects about the size of a sesame seed and are tan to grayish-white in color. They attach themselves to the skin of the head (scalp) and lay eggs (nits) in the hair. Although uncommon, head lice can be spread by sharing clothing or belongings.

You can check for head lice or nits by parting the hair in several spots. Use a magnifying glass and a bright light to help spot them. Lice don’t fly or jump; they move by crawling.
Because head lice can move fast, it may be easier to spot the nits. Nits can look like dandruff. You can identify them by picking up a strand of hair close to the scalp and pulling your fingernail across the area where you suspect a nit. Dandruff will come off easily, but nits will stay firmly attached to the hair.

FDA-approved treatments for head lice include nonprescription (over-the-counter, or OTC) and prescription drugs in shampoo, cream rinse (conditioner), and lotion formulations. Some of these drugs are available in kits that include a small, fine-tooth comb. Separately packaged lice removal combs or comb-like devices are also available and used to remove and/or kill lice and nits.

“Many head lice products are not for use in children younger than 2. So read the label carefully before using a product to make sure it is safe to use on your child,” Brown says.

Talk with your child’s health care professional or your pharmacist about the recommended treatments based on your child’s age and weight. Treatments should be used on children only under the direct supervision of an adult.

Help Your Family Prevent Head Lice

• Teach children to avoid head-to-head contact during play and other activities at home, school, and elsewhere (for example sports, playgrounds, slumber parties, and camps).
• Teach children not to share clothing and supplies, such as hats, scarves, helmets, sports uniforms, towels, combs, brushes, bandanas, hair ties, and headphones.
• Disinfect combs and brushes used by a person with head lice by soaking them in hot water (at least 130°F) for 5 to 10 minutes.
• Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with a person with head lice.
• Vacuum the floor and furniture, particularly where the person with lice sat or laid. Head lice survive less than one or two days if they fall off the scalp and cannot feed.
• Clean items that have been in contact with the head of a person with lice in the 48 hours before treatment. Machine wash and dry clothing, bed linens, and other items using hot water (130°F) and a high heat drying cycle. Clothing and items that are not washable can be dry-cleaned or sealed in a plastic bag and stored for two weeks.
• Do not use insecticide sprays or fogs. They are not necessary to control head lice and can be toxic if inhaled or absorbed through the skin.
• After finishing treatment with lice medication, check everyone in your family for lice after several weeks. If you find live lice, contact your health care professional.

Is mayonnaise effective for treating head lice?

CDC does not have clear scientific evidence to determine if suffocation of head lice with mayonnaise, olive oil, margarine, butter, or similar substances is an effective form of treatment.

If the treatment for head lice doesn’t seem to be working, does this mean the lice are resistant and I need a different treatment?

The following are several common reasons why treatment for head lice may fail sometimes:

1. Misdiagnosis. The symptoms are not caused by an active head lice infestation.
2. Applying the treatment to hair that has been washed with conditioning shampoo or rinsed with hair conditioner. Conditioners can act as a barrier that keeps the head lice medicine from adhering to the hair shafts; this can reduce the effectiveness of the treatment.
3. Not following carefully the instructions for the treatment that is used. Some examples of this include not applying a second treatment if instructed to do so, or retreating too soon after the first treatment before all the nits are hatched and the newly hatched head lice can be killed. Another reason is retreating too late after new eggs have already been deposited.
4. Resistance of the head lice to the treatment used. The head lice may have become resistant to the treatment. If the treatment used does not kill the head lice, your health care provider and pharmacist can help you be sure the treatment was used correctly and may recommend a completely different product if they think the head lice are resistant to the first treatment.
5. Reinfestation. The person was treated successfully and the lice were eliminated, but then the person becomes infested again by lice spread from another infested person. Sometimes reshampooing the hair too soon (less than 2 days) after correctly applying and removing permethin can reduce or eliminate any residual (continued) killing effect on the lice.

Is there a treatment recommendation for certain age groups?

Before treating young children, please consult the child’s doctor, or the health department for the recommended treatment based on the child’s age and weight.

Are there any side effects from using these chemical treatments for head lice?

Treatments for head lice are generally safe and effective when used correctly. Some treatments may cause an itching or a mild burning sensation caused by inflammation of the skin on the scalp. Most products used to treat head lice are pesticides that can be absorbed through the skin. Therefore, all medicines used for the treatment of lice should be used with care and only as directed.

Is it necessary to remove all the nits?

No. The two treatments 9 days apart are designed to eliminate all live lice, and any lice that may hatch from eggs that were laid after the first treatment.

Many nits are more than ¼ inch from the scalp. Such nits are usually not viable and very unlikely to hatch to become crawling lice, or may in fact be empty shells, also known as casings. Nits are cemented to hair shafts and are very unlikely to be transferred successfully to other people.

However, parents may choose to remove all nits found on hair for aesthetic reasons or to reduce the chance of unnecessary retreatment.

Where can I go to have the nits removed from hair?

CDC does not make recommendations about businesses that may offer such services. Your health care provider or local health department may be able to provide additional guidance. Removal of all nits after successful treatment with a pediculicide is not necessary to prevent further spread of head lice. Removal of nits after treatment with a pediculicide may be done for aesthetic reasons, or to reduce diagnostic confusion and the chance of unnecessary retreatment. Because pediculicides are not 100% ovicidal (i.e. do not kill all the egg stages), some experts recommend the manual removal of nits that are attached less than1 cm of the base of the hair shaft.

Why do some experts recommend bagging items for 2 weeks?

Head lice survive less than one or two days if they fall off the scalp and cannot feed. Head lice eggs (nits) cannot hatch and usually die within a week if they do not remain under ideal conditions of heat and humidity similar to those found close to the human scalp. Therefore, because a nit must incubate under conditions equivalent to those found near the human scalp, it is very unlikely to hatch away from the head. In addition, if the egg were to hatch, the newly emerged nymph would die within several hours if it did not feed on human blood.

However, although rarely necessary, some experts recommend that items that may be contaminated by an infested person and that cannot be laundered or dry-cleaned should be sealed in plastic bag and stored for 2 weeks to kill any lice that already are present or that might hatch from any nits that may be present on the items.

Should my pets be treated for head lice?

No. Head lice do not live on pets. Pets do not play a role in the spread of head lice.

Should household sprays be used to kill adult lice?

No. Using fumigant sprays or fogs is NOT recommended. Fumigant sprays and fogs can be toxic if inhaled or absorbed through the skin and they are not necessary to control head lice.

Do I need to have my home fumigated?

No. Use of insecticide sprays or fogs is NOT recommended. Fumigant spray and fogs can be toxic if inhaled or absorbed through the skin and they are not necessary to control head lice.

Routine house cleaning, including vacuuming of carpeting, rugs, furniture, car seats, and other fabric covered items, as well as laundering of linens and clothing worn or used by the infested person is sufficient. Only items that have been in contact with the head of the infested person in the 48 hours before treatment need be considered for cleaning.

Should I have a pest control company spray my house?

No. Use of insecticide sprays or fogs is NOT recommended. Fumigant spray and fogs can be toxic if inhaled or absorbed through the skin and they are not necessary to control head lice.

Routine vacuuming of floors and furniture is sufficient to remove lice or nits that may have fallen off the head of an infested person.

Will laundering kill head lice?

Washing, soaking, or drying items at a temperature greater than 130°F can kill both head lice and nits. Dry cleaning also kills head lice and nits. Only items that have been in contact with the head of the infested person in the 48 hours before treatment should be considered for cleaning.

Although freezing temperatures can kill head lice and nits, several days may be necessary depending on temperature and humidity; freezing is rarely (if ever) needed as a means for treating head lice.

Which medicine is best?

If you aren’t sure which medicine to use or how to use a particular medicine, always ask your physician, pharmacist, or other health care provider. CDC does not make recommendations about specific products. When using a medicine, always carefully follow the instructions contained in the package or written on the label, unless the physician and pharmacist direct otherwise.

What is malathion?

Malathion (Ovide* lotion) is a prescription drug approved by the U.S. Food and Drug Administration (FDA) for the treatment of head lice infestation. The malathion lotion approved in the United States for the treatment of head lice is safe and effective when used as directed. Malathion lotion (Ovide*) is both pediculicidal (kills live lice) and partially ovicidal (kills some lice eggs).

What steps do I follow to treat with malathion?

Step 1: Treat the person(s) infested with head lice:

1. Always follow your physician’s and pharmacist’s instructions and those contained inside the package or written on the label.
2. Carefully apply the malathion lotion to dry hair until the scalp and hair are wet and thoroughly coated, especially behind the ears and on the back of the head and neck.
3. The manufacturer recommends leaving the medication on the hair, uncovered, for 8–12 hours. Allow the hair to dry naturally; do not use an electrical heat source, including a hair dryer or curling iron while the hair is wet. Have the person being treated put on clean clothing once the medication has been applied. Consider treating just before bedtime. Cover any pillow(s) with a towel to keep the medication from staining the pillow.
4. After 8–12 hours, thoroughly shampoo the hair; rinse and use a fine-toothed nit comb, usually included in the package, to remove dead lice and nits from the hair.
5. After treatment, use a fine-toothed nit comb to check the hair for live lice every 2–3 days for 2–3 weeks until sure that all lice are gone.
6. If live lice are found 7 to 9 days after treatment, retreat with a second application of the same medication.

Warnings and Precautions:

1. Malathion may cause stinging, especially if the scalp has open sores from scratching.
2. Keep medication out of the eyes.
3. Malathion is flammable; keep medication and wet hair away from heat sources such as hair dryers, electric curlers, cigarettes, or open flames.
4. Pregnant and nursing mothers should use malathion only after consulting their physician.

Step 2: Consider additional household measures:

Head lice do not live long (less than 1–2 days) if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. You do not need to spend a lot of time or money on housecleaning activities. Follow these steps to help avoid re-infestation by live lice or nits that may have recently fallen off the head or crawled onto clothing or furniture.

1. To kill lice and nits that may have fallen or crawled off the head onto clothing or other articles, machine wash clothing, bed linens, and other items (e.g. towels, stuffed animals, comforters, blankets, etc.) that the infested person wore, slept on, or used during the 2 days before treatment. Use the hot water (at least 130°F) cycle. Dry the laundry using the high heat setting for at least 20 minutes. Items that are not washable can be dry-cleaned OR stored in a sealed plastic bag for 2 weeks.
2. Soak combs and brushes in hot water (at least 130°F) for 5–10 minutes.
3. Vacuum the floor and furniture, particularly where the infested person sat or lay. However, the risk of getting infested by a louse or a nit that was attached to a shed hair that has fallen onto a carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. Spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice that have crawled or nits on shed hairs that may have fallen off the head. Do not use fumigant sprays; they can be toxic if inhaled or absorbed through the skin.

Step 3: Prevent Reinfestation:

Lice are spread most commonly by direct head-to-head (hair-to-hair) contact and much less frequently by sharing clothing or belongings onto which lice or nits may have crawled or fallen. Teach children to avoid types of play and other activities that may spread lice.

• Avoid head-to-head (hair-to-hair) contact during play and other activities at home, school, and elsewhere (slumber parties, sports activities, camp, playground).
• Do not share clothing such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
• Do not share combs, brushes, or towels.
• Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.

My child is under 6 years old and has been diagnosed with head lice. Can I treat him or her with malathion (Ovide* lotion)?

Before treating young children, ask the child’s physician for treatment recommendations. The safety and effectiveness of malathion lotion (Ovide*) has not been established by well controlled trials in children less than 6 years old. Malathion is contraindicated in children younger than 2 years of age.

Are treatment failures with malathion common?

No, however reinfestation can occur.

Is a second treatment needed?

Maybe. If live lice still are found after 7–9 days, a second treatment with malathion lotion may be given. Other family members should be checked for signs of infestation.

Does malathion kill head lice eggs?

Yes. The malathion lotion (Ovide*) available by prescription in the United States can kill some lice eggs.

*Use of trade names is for identification purposes only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.

This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the parasites described above or think that you may have a parasitic infection, consult a health care provider.

Head lice are spread most commonly by direct head-to-head (hair-to-hair) contact. However, much less frequently they are spread by sharing clothing or belongings onto which lice have crawled or nits attached to shed hairs may have fallen. The risk of getting infested by a louse that has fallen onto a carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the scalp.

The following are steps that can be taken to help prevent and control the spread of head lice:

• Avoid head-to-head (hair-to-hair) contact during play and other activities at home, school, and elsewhere (sports activities, playground, slumber parties, camp).
• Do not share clothing such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
• Do not share combs, brushes, or towels. Disinfest combs and brushes used by an infested person by soaking them in hot water (at least 130°F) for 5–10 minutes.
• Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.
• Machine wash and dry clothing, bed linens, and other items that an infested person wore or used during the 2 days before treatment using the hot water (130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry-cleaned OR sealed in a plastic bag and stored for 2 weeks.
• Vacuum the floor and furniture, particularly where the infested person sat or lay. However, spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice or nits that may have fallen off the head or crawled onto furniture or clothing.
• Do not use fumigant sprays or fogs; they are not necessary to control head lice and can be toxic if inhaled or absorbed through the skin.

To help control a head lice outbreak in a community, school, or camp, children can be taught to avoid activities that may spread head lice.

You should examine your child’s head, especially behind the ears and at the nape of the neck, for crawling lice and nits if your child exhibits symptoms of a head lice infestation. If crawling lice or nits are found, all household members should be examined for crawling lice and nits every 2–3 days. Persons with live (crawling) lice or nits within ¼ inch or less of the scalp should be treated.

To eliminate head lice successfully, it is very important that all treatment instructions and steps be carefully followed and completed.

CDC does not make recommendations as to what specific product or products should be used to treat individuals. Both over-the-counter and prescription products are available. You may wish to contact your doctor, pharmacist, or health department for additional information about which product they recommend.

Children diagnosed with live head lice do not need to be sent home early from school; they can go home at the end of the day, be treated, and return to class after appropriate treatment has begun. Nits may persist after treatment, but successful treatment should kill crawling lice.

Head lice can be a nuisance but they have not been shown to spread disease. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice.

Students diagnosed with live head lice do not need to be sent home early from school; they can go home at the end of the day, be treated, and return to class after appropriate treatment has begun. Nits may persist after treatment, but successful treatment should kill crawling lice.

Head lice can be a nuisance but they have not been shown to spread disease. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice.

Both the American Academy of Pediatrics (AAP) and the National Association of School Nurses (NASN) advocate that “no-nit” policies should be discontinued. “No-nit” policies that require a child to be free of nits before they can return to schools should be discontinued for the following reasons:

• Many nits are more than ¼ inch from the scalp. Such nits are usually not viable and very unlikely to hatch to become crawling lice, or may in fact be empty shells, also known as ‘casings’.
• Nits are cemented to hair shafts and are very unlikely to be transferred successfully to other people.
• The burden of unnecessary absenteeism to the students, families and communities far outweighs the risks associated with head lice.
• Misdiagnosis of nits is very common during nit checks conducted by nonmedical personnel.