Information
Head lice, or Pediculus humanus capitis, are parasitic insects that feed on human blood. Head lice live primarily on the scalp and hair shafts. Adult head lice are roughly 2 – 3 mm long (about the size of a sesame seed).
Both over-the-counter and prescription medications are available to treat head lice in your hair (infestation).
Head lice do not transmit any disease and therefore are not considered a health hazard.
Who is at risk
In the United States, infestation with head lice is most common among preschool- and elementary school-age children and their household members and caretakers.
How it spreads
Head lice mainly spread by direct contact with the hair of a person infested with lice. Head lice move by crawling; they cannot hop or fly. Adult lice can live on a person's head for about 30 days. However, they will die within two days if they fall off a person and cannot feed. Adult female head lice are usually larger than males and can lay about six eggs each day. Nits (lice eggs) cannot hatch and usually die within a week if they are not kept at the same temperature as those found close to the scalp. Nits take about a week (range 6 – 9 days) to hatch into nymphs (young lice). Nymphs look similar to adult lice but are very small (size of a pinhead); they take about seven days to mature into adult lice.
The most common way to get head lice is by head-to-head contact with a person who already has head lice. This contact can be common among children playing at places like school or the home. Getting head lice is not related to cleanliness of you or your environment.
Contracting lice from a wig or hairpiece is extremely unlikely. Especially if the wig or hairpiece hasn't been worn in the past 48 hours by a person with head lice. Lice are usually destroyed by brushes and combs reducing the risk of transmission from sharing these items. Getting lice from sharing clothing and towels is also unlikely.
Head lice can survive under water for several hours but are unlikely to spread in a swimming pool. Chlorine levels in pool water do not kill head lice.
Animals do not get or spread head lice.
Prevention
Take these steps to help prevent and control the spread of head lice:
- Avoid head-to-head (hair-to-hair) contact during play and other activities at home, school, and elsewhere (sports activities, playground, slumber parties, camp).
- Do not share clothing such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
- Thoroughly clean combs and brushes used by an infested person by soaking them in hot water (at least 130°F) for 5 – 10 minutes.
- Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with a person infested with head lice.
- Machine wash and dry clothing, towels, bed linens, and other items that a person infested with lice wore or used during the two days before treatment. Use the hot water (130°F) laundry cycle and the high heat drying cycle. If you can't wash or dry clean items, seal them in a plastic bag and store them for two weeks.
- Vacuum the floor and furniture, particularly where the infested person sat or lay. However, spending much time and money on housecleaning activities is not necessary to avoid re-infestation by lice or nits that may have fallen off the head or crawled onto furniture or clothing.
- Do not use fumigant sprays or fogs; they are not necessary to control head lice and can be toxic if inhaled or absorbed through the skin.
Resources
For more information, visit the Centers for Disease Control and Prevention (CDC) website on head lice or view the following resources:
Page last reviewed/updated: May 2025