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Head Lice

(Pediculosis)

Definition

Head lice (lice is plural, louse is singular) are tiny insect-like animals called arthropods that may live on the head and cause itching. Head lice may also live in the eyebrows, eyelashes, and beard. However, some infestations in these areas are from a related species called pubic lice (crabs).

Head Lice

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Causes    TOP

Head lice is spread by personal contact and by sharing combs, brushes, hats, and other personal items.

Risk Factors    TOP

This condition is more common in young children.

Factors that may increase the chance of lice include:

  • Sharing combs, brushes, hats, and other personal items
  • Personal contact with people who may have lice

Symptoms    TOP

Some people with head lice do not have any symptoms.

When symptoms do occur, they may include:

  • Extreme itchiness
  • Skin breaks and possible infection caused by scratching
  • Swollen lymph nodes
  • Bacterial infection—if scratching causes open areas on the scalp

Diagnosis    TOP

You will be asked about your symptoms and medical history. A physical exam will be done. Your head and scalp will be examined for lice and lice eggs (nits).

Do not self-diagnose and self-treat head lice. Some treatments can cause irritation and should only be used by people who have the infestation.

Treatment    TOP

Treating head lice involves removing eggs and killing lice so that they can't continue to lay eggs. Treatment may be difficult. In some regions, lice have become resistant to many commonly used medications. Some experts recommend that treatment be given only when live adult lice are seen.

Methods include:

  • Applying over-the-counter shampoo containing the insecticide permethrin. It is important to use medications as directed. Retreatment at 7-10 days is usually required to kill any lice that hatch from unremoved eggs.
  • Removing lice on the eyelashes, which may be difficult. Tweezers can be used to pick them off. Vaseline may be used to coat the eyelashes and kill the lice.
  • Unless instructed otherwise, remove eggs manually with specially designed combs. Eggs stick firmly to hair. Over-the-counter products that loosen the eggs may help with removal.

Over-the-Counter Medication

Most cases of head lice can be treated with over-the-counter preparations. However, there is increasing resistance to the medications permethrin and pyrethrin in the United States. There are other treatments that may be effective, such as herbal remedies that contain coconut oil and anise.

Prescription Medication

Prescription creams or lotions may be prescribed to treat head lice. These include benzyl alcohol lotion, ivermectin lotion, and malathion lotion.

In certain cases, your doctor may prescribe lindane. Lindane is neurotoxic and carries a black box warning. Follow the instructions carefully. It should only be prescribed to patients who are unable to take other medications or who have not responded to them. According to the Food and Drug Administration’s warning, lindane can rarely cause serious side effects, including seizure and death. Those especially susceptible are infants, the elderly, children and adults weighing under 110 lbs, and individuals with other skin conditions. Lindane is toxic and should not be overused. Patients are given small amounts (1-2 ounces) of the shampoo or lotion and instructed to apply a thin layer and not to reapply.

Prevention    TOP

Lice are common, especially in children. To prevent outbreaks of head lice:

  • Watch for signs of head lice, such as frequent head scratching.
  • Don't share combs, brushes, hats, or other personal items with people who may have lice.
  • Avoid close personal contact with people who may have lice.
  • If you or your children have head lice, thoroughly wash and dry combs, brushes, hats, clothing, bedding, and stuffed animals. Also, vacuum carpeting and car seats.
  • If your children get head lice, notify their school, camp, daycare provider, and their friends' parents.
  • Check all family members for lice and eggs at least once a week.

RESOURCES

Centers for Disease Control and Prevention
http://www.cdc.gov
Nemours Kids Health
http://kidshealth.org

CANADIAN RESOURCES

Caring for Kids—Canadian Paediatric Society
http://www.caringforkids.cps.ca

References:

Lindane shampoo and lindane lotion. Food and Drug Administration website. Available at:
...(Click grey area to select URL)
Updated July 16, 2015. Accessed February 9, 2016.
Medication guide lindane lotion. Food and Drug Administration website. Available at:
...(Click grey area to select URL)
Updated August 2007. Accessed February 9, 2016.
Medication guide lindane shampoo. Food and Drug Administration website. Available at:
...(Click grey area to select URL)
Updated August 2007. Accessed February 9, 2016.
Head lice. American Academy of Dermatology website. Available at: https://www.aad.org/public/diseases/contagious-skin-diseases/head-lice. Accessed February 9, 2016.
Head lice treatment. Centers for Disease Control and Prevention website. Available at:
...(Click grey area to select URL)
Updated December 28, 2015. Accessed February 9, 2016.
Revised lindane lotion label. Food and Drug Administration website. Available at:
...(Click grey area to select URL)
Accessed February 9, 2016.
Revised lindane shampoo label. Food and Drug Administration website. Available at:
...(Click grey area to select URL)
Accessed February 9, 2016.
Roberts RJ. Clinical practice. Head lice. N Engl J Med. 2002;347(17):1381-1382.
12/14/2009 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T116514/Head-lice: Burgess IF, Brunton ER, Burgess NA. Clinical trial showing superiority of a coconut and anise spray over permethrin 0.43% lotion for head louse infestation, ISRCTN96469780. Eur J Pediatr. 2010;169(1):55-62.
11/26/2012 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T116514/Head-lice: Pariser D, Meinking T, Bell M, et al. Topical 0.5% ivermectin lotion for treatment of head lice. N Engl J Med. 2012;367(18):1687-1693..
Last reviewed March 2017 by EBSCO Medical Review BoardDavid L Horn, MD
Last Updated: 2/9/2016

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