Head Lice

Medically Reviewed By William C. Lloyd III, MD, FACS
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What are head lice?

Head lice are tiny insects that live on the scalp and hair. Occasionally, head lice can be found in the eyebrows and eyelashes. Head lice are parasites that live off human blood. They feed by biting the scalp, and simultaneous exposure to lice saliva leads to intense itching.

When you have head lice, it is called pediculosis. The adult insect is called a louse and is about the size of a large grain of sand. Because they are so small, head lice can be hard to spot. Head lice eggs (nits), though even smaller, are attached to the base of hair shafts and are easier to find. The nits resemble dandruff flakes, but they aren’t easily brushed off like dandruff flakes. Instead, they stay attached to the hair shaft until you pick them off. Nits are easiest to spot around the neck and ears in bright sunlight or with a very bright light. The adult louse can live on the scalp for about 30 days and the nits can survive for two weeks on a hair shaft.

Lice do not have wings and do not hop or jump, but they are able to crawl very quickly. This allows them to spread easily and quickly through close contact with someone who is infested. You can also get head lice from sharing hairbrushes, combs, hats, scarves, hair accessories, towels, pillows, beds, or stuffed animals with someone who is already infested. Frequent bathing and hair washing with general shampoos does not prevent or cure head lice. Therefore, having head lice is not a sign of poor personal hygiene.

Although anyone can get head lice, it most commonly occurs in children three to 12 years of age. In the United States, approximately six to 12 million children have head lice infestations each year (Source: AAP). After the common cold, head lice is the most common communicable disease among children. Children of this age tend to play closely with each other and share items that can transfer head lice. Adults and family members of infested children should be checked for head lice and treated if necessary. The presence of nits does not automatically mean active infestation. Nits can persist for months after treatment.

Many children with head lice have no symptoms. Some children can harbor a large colony without apparent symptoms. The main symptoms of head lice are intense scalp itching; a tickling or crawling sensation on the scalp; small red bumps or sores on the scalp, neck or shoulders; and the presence of nits. Because head lice are most active in the dark, itching can disturb your sleep.

Head lice can be treated and cured. Both over-the-counter (OTC) and prescription products are available to treat head lice. Always talk with your doctor before using any of the OTC products because they contain pesticides that may be harmful for certain people, including women who are pregnant or nursing and people with asthma or allergies. It is unlikely that any of these products will kill all the nits, so an important part of treatment is using a nit comb to remove the nits. You will also need to use hot water to wash any articles that came in contact with the infested person, including pillows, bed linens, towels, and stuffed animals.

Head lice do not carry or spread disease and usually do not lead to serious complications. However, a secondary skin infection with bacteria and other germs can occur from scratching the scalp. Seek prompt medical care if you have any symptoms of head lice, symptoms continue after home treatment, or you have red, tender skin on the scalp, which may be a sign of infection.

What are the symptoms of head lice?

Head lice can be difficult to see because the adult insects move quickly and are more active in the dark. Head lice infestation is often diagnosed based on the symptoms and possibly, the appearance of the eggs (nits), which are easier to see than adult lice.

Symptoms of head lice infestation include:

  • Itching of the scalp that can be very intense and continuous

  • Presence of nits on the base of the hair shafts at the scalp

  • Sleep problems

  • Small red bumps on the scalp, neck and shoulders, which may turn into sores from scratching

  • Tickling or crawling feeling on the scalp

Symptoms that might indicate a serious condition

Seek prompt medical care if you, or your child, have any symptoms of head lice or if symptoms persist despite treatment. Although head lice do not carry or spread disease, your skin can become infected by bacteria or other germs from scratching. Signs of a possible infection include red, tender scalp skin.

What causes head lice?

Head lice are wingless insects that move by crawling. They cannot fly, jump or hop. They spread quickly and are transferred from person to person by close, head-to-head contact with someone who is already infested. You can also get head lice from someone who is infested by sharing the following items:

  • Beds and bed linens

  • Carpet (lying on the carpet or a rug with someone who is infested)

  • Combs

  • Couches

  • Hair accessories, such as barrettes and ribbons

  • Hairbrushes

  • Hats, coats or scarves

  • Pillows

  • Sports uniforms

  • Stuffed animals

  • Towels

Head lice are not an indication of low social or financial status and are not caused or transferred to other people because of poor personal hygiene or through contact with pets, such as dogs and cats.

What are the risk factors for head lice?

Head lice are spread mainly through close, head-to-head contact with someone who is already infested. Children between the ages of three and 12 years are at highest risk of getting head lice because they often play in close contact with each other, such as when roughhousing. This type of play and close contact can occur at:

  • Camps

  • Day care centers

  • Home

  • Playgrounds

  • Preschools

  • Schools

  • Slumber parties

  • Sports activities

Sharing personal items is a less common way to get head lice. However, you should teach children not to share items, such as combs, hairbrushes, hats, scarves, pillows, towels, or stuffed animals. Girls may be more likely to get head lice in this way because they are more likely to share hair-related items.

Reducing your risk of head lice

You can lower your or your child’s risk of catching or spreading head lice by:

  • Avoiding head-to-head contact during play and other activities
  • Routinely inspecting children’s scalp and hair after bathing
  • Following the treatment plan you and your healthcare provider design specifically for you
  • Teaching your children not to share items, such as combs, hairbrushes, hats, scarves, pillows, towels, or stuffed animals
  • Using hot water to wash and high heat to dry all bed linens, towels, clothing, and stuffed animals that have been in contact with an infested person
  • Vacuuming all furniture, rugs and carpets that have been in contact with an infested person

Head lice are not able to survive for long off humans. So, it is not necessary and may be dangerous to use fumigant lice sprays.

How are head lice treated?

Head lice are treatable and curable. Completely eradicating an infestation can be a challenge and involves several steps. To prevent reinfestation within a family, all family members should be checked for any signs of an infestation. Some health experts recommend treating anyone who shares a bed with an infested person regardless of whether he or she has signs of an active infestation or not. Treatment involves topical medication for the scalp and steps to kill lice and nits in the home and on personal items. Lice do not survive longer than 48 hours without a human host.

Over-the-counter (OTC) head lice treatments

Shampoos and lotions are available OTC to treat head lice. These products contain pesticides, so it is important to check with your physician before using them. Other products are often recommended if you are pregnant or nursing, if you have asthma or allergies, for infants, and in some other cases. Always read and follow the complete directions and warnings on OTC products. OTC head lice products include:

  • Permethrin (Nix)

  • Pyrethrins combined with piperonyl butoxide (Rid, Pronto, Licide, A-200)

These products will kill adult insects, but may not kill all the nits. Retreatment within nine days is usually recommended to kill any nits that may hatch after the first treatment. You will also need to use a nit comb to manually remove attached nits and help prevent a reinfestation. Generally, nit combing should be repeated every two to three days.
Follow the directions provided on the labeling of these products. Never use pesticide products around your eyes. If lice or nits are present in your eyelashes or eyebrows, contact your healthcare provider. You also need to contact your healthcare provider if head lice persist despite treatment and retreatment with an OTC product.

Schools, camps, and other organizations will generally require documentation from your physician or healthcare provider that the infestation is cured before allowing a child back in the activity.

Prescription head lice treatments

Prescription products are also available to treat head lice. These products are used when home treatment with OTC products fails or may be recommended by your healthcare provider as a first line of treatment in some cases. Some prescription products may also be safer to use in pregnant or nursing women or people who have asthma or allergies. Prescription products include:

  • Benzyl alcohol lotion (Ulesfia)

  • Lindane, although it is no longer recommended as a first-line treatment of head lice due to toxicity

  • Malathion (Ovide)

  • Spinosad (Natroba)

Similar to OTC products, prescription products are not likely to kill all nits. Therefore, manual nit removal with the aid of a nit comb and retreatment may be necessary.

Other treatments for head lice

Other methods for controlling symptoms and preventing a reinfestation include:

  • Soaking combs, brushes, and other hair accessories in hot water for five to 10 minutes

  • Taking antihistamines to relieve itching

  • Using hot water to wash and high heat (at least 130 degrees Fahrenheit) to dry all bed linens, towels, clothing, and stuffed animals that have been in contact with an infested person

  • Vacuuming all furniture and carpets that have been in contact with an infested person

What are the potential complications of head lice?

Head lice do not carry or spread disease, but complications from a head lice infestation are possible. You can best treat head lice and lower your risk of complications by following the treatment plan you and your healthcare provider design specifically for you. Complications of head lice include:

  • Reinfestation if not properly treated or if the people close to you or your child are not thoroughly treated

  • Secondary skin infection by bacteria and other germs from scratching

  • Sleep problems because head lice are most active in the dark

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 19
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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