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 crab lice (pubic lice).

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Causes

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

Risk Factors

This condition is more common in young children.

Factors that may increase the chances of lice:

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

Symptoms

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

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

Treating head lice involves removing eggs and killing lice so that they cannot 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.

Prevention

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

• Watch for signs of head lice such as frequent head scratching.
• Do not 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.