Head Lice

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

  • Causes

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

  • Definition

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

    Head Lice
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  • Diagnosis

    The doctor will ask about your symptoms and medical history. A physical exam will be done. The doctor will examine your head and scalp for lice and lice eggs (called "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.

  • Prevention


    Lice are common, especially in children. While no records are kept for accurate counts, some estimates are that as many as 10-15 million persons annually develop head lice in the United States. 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 lis 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.

  • Risk Factors


    A risk factor is something that increases your chance of getting a disease or condition.
    Risk factors include:

    • Age: childhood
    • Sharing combs, brushes, hats, and other personal lis
    • Personal contact with people who may have lice

  • Symptoms


    Symptoms include:

    • Extreme itchiness
    • Skin breaks and possible infection (caused by scratching)
    • Swollen lymph nodes
    • Bacterial infection (if scratching causes open areas on the scalp)
    • Some persons with head lice do not have symptoms.

  • Treatment

    Treating head lice involves removing eggs and killing lice so that they can't continue to lay eggs. Treatment may be difficult because in some regions lice have become resistant to many of the commonly used medicines. 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 very important to use medicines 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. Products such as “Clear," which loosen the eggs, may assist in removal.