Swedish Kids Symptom Checker

Swedish Kids Symptom Checker

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Lice - Head

1. Does this describe your child's symptoms?


From the CDC's Public Health Image Library (http://phil.cdc.gov), ID#377, in the public domain.

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

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.


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.

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.


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.


  • A scalp infection with tiny gray bugs called lice


  • 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, 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 because they 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 and very white in color.
  • Off the scalp, nits can’t survive over 2 weeks.
  • Adult lice survive 3 weeks on the scalp or 24 hours off the scalp.


  • A tiny insect the size of a sesame seed

Transmission of Head Lice: Live Lice, Not Nits

  • Only live lice can transmit lice to another child.
  • Nits (lice eggs) cannot transmit lice because they are attached to the child’s hair.
  • Almost all transmission is from direct head-to-head (hair-to-hair) contact. Lice cannot jump or fly to another person’s hair.
  • Indirect transmission of lice from hats, caps, hair brushes, combs, headphones and other objects is very uncommon.
  • Most transmission of lice occurs at home, not school or other public places. Sleepovers and bed-sharing are a major source.

Return to School

  • Your child can return to child care or school after 1 treatment with the anti-lice shampoo.
  • A child with head lice doesn’t need to miss any school or child care because of the presence of nits, because nits are not contagious.

2. When to Call Your Doctor

Call Your Doctor During Weekday Office Hours If

  • You think your child needs to be seen
  • Diagnosis of head lice is uncertain
  • New head lice or nits appear after treatment
  • Scalp rash or itch lasts over 7 days after treatment
  • You have other questions or concerns

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

  • Age under 2 months old (Reason: have your doctor recommend the safest lice medicine)
  • Scalp looks infected (e.g., pus, soft scabs, open sores)

Parent Care at Home If

  • Head lice and you don't think your child needs to be seen


  • Reassurance:
    • Head lice can be treated at home.
    • With careful treatment, all lice and nits (lice eggs) are usually killed.
    • There are no lasting problems from having head lice.
    • They do not carry any diseases.
    • They do not make your child feel sick.
  • Nix: Buy Nix anti-lice creme rinse (no prescription needed) and follow package directions.
    • First, wash the hair with a regular shampoo and towel dry it before using the anti-lice creme. Do NOT use a conditioner or creme rinse after shampooing (Reason: interferes with Nix).
    • Pour 2 ounces (full bottle or 60 ml) of Nix 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 necessary, 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 or it won't kill all the lice. Then rinse the hair thoroughly 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:  
    • Only live lice can transmit lice to another child.
    • Nits (lice eggs) do not transmit lice.
    • Most treated nits (lice eggs) are dead after the first treatment with Nix. The others will be killed with the 2nd treatment in 9 days.
    • Removing the dead nits is helpful for esthetic reasons and so other people won't think your child still has untreated lice.
    • Nits can be removed by backcombing with a special nit comb or pulling them out individually. This is time-consuming.
    • Wetting the hair makes removal easier, but avoid any products that claim they loosen the nits. (Reason: They can interfere with the ability of Nix to stay on the hair and keep working.)
    • Nit removal is not urgent and should not interfere with the return to school.
    • Some schools, however, have a no-nit policy and will not allow children to return if nits are visible. The American Academy of Pediatrics and the National Association of School Nurses recommend that all no-nit policies be abandoned. If your child's school has a no-nit policy, your child's doctor may be able to help.
  • Hairwashing Precautions to Help Nix Work:
    • Don't wash the hair with shampoo until 2 days after lice treatment
    • Avoid hair conditioners before treatment and for 2 weeks afterwards (Reason: coats the hair and interferes with Nix)
  • Contagiousness of Lice/ Return to School:  
    • Lice are transmitted by close contact (they cannot jump or fly).
    • Your child can return to child care or 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, or someone has the new onset of an itchy scalp rash, they also should be treated with anti-lice shampoo.
    • Bedmates of children with lice should also be treated.  If in doubt, have your child examined for lice.
    • Re-emphasize not sharing combs and hats.  
    • Also notify the school nurse or child care center director so she can check other students in your child's class/center.
  • 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.) Just 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, pillow cases, and any clothes worn in the past 2 days in hot water (130° F or 54° C) kills lice and nits.
    • Optional step (probably not necessary): Items that can't be washed (e.g., hats, coats, or scarves) should be set aside in sealed plastic bags for 2 weeks (the longest period that nits can survive).
  • Expected Course:

    • With treatment, all lice and nits should be killed.
    • A recurrence usually means another contact with an infected person, the shampoo wasn't left on for 10 minutes, hair conditioner was used or the treatment wasn't repeated in 9 days.
  • Call Your Doctor If:
    • New lice or nits appear in the hair
    • Scalp rash or itch lasts over 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 Nix Treatment Failures:
    • Go to your drugstore and buy Cetaphil cleanser (no prescription needed) in the soap department. 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 then it would if the hair was just wet with water.
    • 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 are available online: www.nuvoforheadlice.com
  • And remember, contact your doctor if your child develops any of the 'Call Your Doctor' symptoms.


  • This information is not intended 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.
  • Author and Senior Reviewer: Barton D. Schmitt, M.D.
  • Last Reviewed: 11/16/2011 10:27:21 AM
  • Last Revised: 11/16/2011 10:27:21 AM
  • Content Set: Pediatric HouseCalls Symptom Checker
  • Copyright 1994-2012 Barton D. Schmitt, M.D.
If this is an emergency call 911 immediately.

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