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Lice - Head

Definition

  • A scalp infection with tiny gray bugs called lice
  • Many white eggs (nits) are seen in the hair

Symptoms

  • Itching of the scalp is the main symptom.
  • A scalp rash may be present. The back of the neck is the favorite area.

Lice and Nits

  • Lice are 1/16-inch (2 mm) long gray-colored bugs. They move quickly and are difficult to see.
  • Nits are white eggs firmly attached to hair shafts near the skin. Unlike dandruff or sand, nits can't be shaken off the hair shafts.
  • The nits are easier to see than the lice. Nits are white and very numerous.

Lifespan of Lice

  • The nits (eggs) hatch into lice in about 1 week.
  • Nits (eggs) that are over ½ inch (1 cm) from the scalp are empty egg cases. They are very white in color.
  • Off the scalp, nits (eggs) can’t survive over 2 weeks.
  • Adult lice survive 3 weeks on the scalp or 24 hours off the scalp.

Cause

  • A tiny insect the size of a sesame seed

Transmission of Head Lice: Live Lice, Not Nits

  • Only live lice can give lice to another child.
  • Nits (lice eggs) cannot pass on lice. Nits are attached to the child’s hair.
  • Almost all spread of lice is from direct hair-to-hair contact. Lice cannot jump or fly to another person’s hair.
  • The spread of lice from hats, hair brushes or combs is not common. Headphones and other objects also do not usually spread lice.
  • Most often, the spread of lice to others occurs at home, not school. Sleepovers and bed-sharing are a major source.

Return to School

  • Your child can return to school after 1 treatment of anti-lice shampoo.
  • A child with nits only doesn't need to miss any school or child care. Nits do not spread to others, nor do they cause lice in others.

Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information. For more information, click here.

Author and Senior Reviewer: Barton D. Schmitt, M.D.
Last Reviewed: 4/8/2014
Last Revised: 4/10/2014
Content Set: Pediatric HouseCalls Symptom Checker
Copyright 1994-2013 Barton D. Schmitt, M.D.

When To Call

Call Your Doctor Within 24 Hours (between 9 am and 4 pm) If

  • Age less than 2 months old
  • Scalp looks infected (such as pus, soft scabs, open sores)

Call Your Doctor During Weekday Office Hours If

  • ​You think your child needs to be seen
  • Not sure your child has head lice
  • New head lice or nits are seen after treatment
  • Scalp rash or itch lasts more than 7 days after treatment
  • You have other questions or concerns

Parent Care at Home If

  • Head lice

Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information. For more information, click here.

Author and Senior Reviewer: Barton D. Schmitt, M.D.
Last Reviewed: 4/8/2014
Last Revised: 4/10/2014
Content Set: Pediatric HouseCalls Symptom Checker
Copyright 1994-2013 Barton D. Schmitt, M.D.

Care Advice

What You Should Know:

  1. Head lice can be treated at home.
  2. With careful treatment, all lice and nits (lice eggs) are usually killed.
  3. There are no lasting problems from having head lice.
  4. They do not carry any diseases.
  5. They do not make your child feel sick.
  6. Here is some care advice that should help.
  7. Buy anti-lice creme rinse (e.g. Nix - no prescription needed) and follow package directions.
    • First, wash the hair with a regular shampoo. Then, towel dry it before using the anti-lice creme. Do NOT use a conditioner or creme rinse after shampooing. Reason: It will interfere with anti-lice creme.
    • Pour 2 ounces (full bottle or 60 ml) of anti-lice creme into damp hair. People with long hair may need to use 2 bottles.
    • Work the creme into all the hair down to the roots.
    • If needed, add a little warm water to work up a lather.
    • Nix is safe above 2 months old.
    • Leave the shampoo on for a full 10 minutes. If you don't, it won't kill all the lice. Then rinse the hair well with water and dry it with a towel.  
    • REPEAT the anti-lice shampoo in 9 days to kill any nits that survived.
    Remove the Dead Nits:  
    • ​Nit removal is not necessary. It should not interfere with the return to school.
    • Some schools, however, have a no-nit policy. They will not allow children to return if nits are seen. The American Academy of Pediatrics advise that no-nit policies be no longer used. The National Association of School Nurses also takes this stand. If your child's school has a no-nit policy, call your child's doctor.
    • Reasoning: only live lice can spread lice to another child. One treatment with Nix kills all the lice.
    • Nits (lice eggs) do not spread lice. Most treated nits (lice eggs) are dead after the first treatment with Nix. The others will be killed with the 2nd treatment.
    • Removing the dead nits is not essential or urgent. However, it prevents others from thinking your child still has untreated lice.
    • Nits can be removed by backcombing with a special nit comb.
    • You can also pull them out one at a time. This will take a lot of time.
    • Wetting the hair with water makes removal easier. Avoid any products that claim they loosen the nits. (Reason: Can interfere with anti-lice creame)
    Hairwashing Precautions to Help Nix Work:
    • Don't wash the hair with shampoo until 2 days after anti-lice creame treatment.
    • Avoid hair conditioners before treatment. Do not use them for 2 weeks after treatment. Reason: Coats the hair and interferes with anti-lice creame.
    Return to School:  
    • Lice are spread by close contact. They cannot jump or fly.
    • Your child can return to school after 1 treatment with the anti-lice shampoo.
    • Check the heads of everyone else living in your home.  If lice or nits are seen, they also should be treated. Use the anti-lice shampoo on them as well. Also, anyone with an itchy scalp rash should be treated.
    • Bedmates of children with lice should also be treated.  If in doubt, have your child checked for lice.
    • Remind your child not to share combs and hats.  
    • Be sure to tell the school nurse or child care center director. She can check other students in your child's class.
    Cleaning the House:
    • Lice that are off the body rarely cause reinfection. Reason: Lice can't live for over 24 hours off the human body. Vacuum your child's room.
    • Soak hair brushes for 1 hour in a solution containing some anti-lice shampoo.
    • Wash your child's sheets, blankets, and pillow cases. Wash any clothes worn in the past 2 days. Wash in hot water (130° F or 54° C). This kills lice and nits.
    • Items that can't be washed (hats, coats, or scarves) should be set aside. Put them in sealed plastic bags for 2 weeks. This is the longest period that nits can survive. (Note: This is an option. This step probably is not needed.)
    What to Expect:
    • With treatment, all lice and nits should be killed.
    • If lice come back, it can mean another contact with an infected person. It can also be that the shampoo wasn't left on for 10 minutes. It may also mean that hair conditioner was used.
    • Also, make sure the anti-lice creame is repeated in 9 days. If you don't, the lice may come back.
    Call Your Doctor If:
    • New lice or nits are seen in the hair
    • Scalp rash or itch lasts more than 1 week after the anti-lice shampoo
    • Sores on scalp start to spread or look infected
    • Your child becomes worse
    Extra Care Advice - Cetaphil Cleanser for Anti-Lice Creame Treatment Failures:
    • Go to your drugstore and buy Cetaphil cleanser in the soap department. No prescription is needed. It works by coating the lice and suffocating them.
    • Apply the Cetaphil cleanser throughout the scalp to dry hair.
    • After all the hair is wet, wait 2 minutes for Cetaphil to soak in.
    • Comb out as much excess cleanser as possible.
    • Blow dry your child's hair. It has to be thoroughly dry down to the scalp to suffocate the lice. Expect this to take 3 times longer than normal drying.
    • The dried Cetaphil will smother the lice. Leave it on your child's hair for at least 8 hours.
    • In the morning, wash off the Cetaphil with a regular shampoo.
    • To cure your child of lice, REPEAT this process twice in 1 and 2 weeks.
    • The cure rate can be 97%.
    • Detailed instructions can be found online: www.nuvoforheadlice.com
    And remember, contact your doctor during weekday office hours if you are not sure your child has head lice.  
    To find a pediatrician, click here.

    Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information. For more information, click here.

    Author and Senior Reviewer: Barton D. Schmitt, M.D.
    Last Reviewed: 4/8/2014
    Last Revised: 4/10/2014
    Content Set: Pediatric HouseCalls Symptom Checker
    Copyright 1994-2013 Barton D. Schmitt, M.D.

Photos

 

Head Lice - Searching Hair

An infestation is diagnosed by looking closely through the hair and scalp for nits, nymphs, or adults. Finding a nymph or adult may be difficult; there are usually few of them and they can move quickly from searching fingers. If crawling lice are not seen, finding nits within a 1/4 inch of the scalp confirms that a person is infested and should be treated. If you only find nits more than 1/4 inch from the scalp (and don't see a nymph or adult louse), the infestation is probably an old one and does not need to be treated.

If you are not sure if a person has head lice, the diagnosis should be made by your health care provider, school nurse, or a professional from the local health department or agricultural extension service.

Source: CDC DPD

This work is in the public domain because it is a work of the United States federal government.

Text and image reproduced from the CDC Division of Parasitic Diseases.

 

 

Head Lice Size Compared to a Penny

Egg (Nit): Nits are head lice eggs. They are very small, about the size of a knot in thread, hard to see, and are often confused for dandruff or hair spray droplets. Nits are laid by the adult female at the base of the hair shaft nearest the scalp. They are firmly attached to the hair shaft. They are oval and usually yellow to white. Nits take about 1 week to hatch. Eggs that are likely to hatch are usually located within 1/4 inch of the scalp.

Nymph: 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 7 days after hatching. To live, the nymph must feed on blood.

Adult: The adult louse is about the size of a sesame seed, has six legs, and is tan to greyish-white. In persons with dark hair, the adult louse will look darker. Females, which are usually larger than the males, lay eggs. 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 2 days.

Source: CDC DPD

This work is in the public domain because it is a work of the United States federal government.

Text and image reproduced from the CDC Division of Parasitic Diseases.

 

 

Head Louse (Female)

Source: CDC PHIL

From the CDC's Public Health Image Library, ID#377, in the public domain.

Content Providers: CDC / Dr. Dennis D. Juranek.

Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information. For more information, click here.

Author and Senior Reviewer: Barton D. Schmitt, M.D.
Last Reviewed: 4/8/2014
Last Revised: 4/10/2014
Content Set: Pediatric HouseCalls Symptom Checker
Copyright 1994-2013 Barton D. Schmitt, M.D.

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