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, but sometimes infestations in these areas are from a related species called pubic lice.
Head lice spread by personal contact and by sharing combs, brushes, hats, and other personal items.
A risk factor is something that increases your chance of getting a disease or condition.
- Age: childhood
- Sharing combs, brushes, hats, and other personal items
- Personal contact with people who may have lice
- 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
The doctor will ask about your symptoms and medical history, and perform a physical exam. The doctor will examine your head and scalp for lice and lice eggs (called "nits").
Do not self-diagnose and self-treat head lice, because some treatments can cause irritation and should only be used by people who have head lice.
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 treatments. Many experts recommend that treatment be given only when live adult lice are seen.
- Apply over-the-counter shampoo containing the insecticide, permethrin. In areas with high levels of resistance to permethrin other doctor-prescribed treatments may be used. These include lindand and malathione. Special precautions may apply to these prescription treatments which should not be used in pregnant or nursing women or children under the age of two. It is very important to use medications as directed. Retreatment at 7-10 days is usually required to kill any lice that hatch from unremoved eggs.
- Lice on the eyelashes can be very difficult to remove. Forceps can be used to pick them off. Vaseline may be used to coat the eyelashes and kill the lice.
- Unless instructed otherwise, manually remove eggs with specially designed combs. Eggs stick firmly to hair, and products such as “Clear” that loosen the eggs may assist in removal.
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 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, and 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.