EVERYTHING YOU’VE EVER WANTED TO KNOW ABOUT HEAD LICE
Each year in the United States, between 6 and 12 million children are infested with head lice, according to the FDA. This common issue doesn’t just stop with kids—parents and other family members frequently contract head lice as well, often through close contact or shared items like brushes, hats, and bedding. Lice are incredibly contagious, and managing an infestation can be both frustrating and overwhelming for families.
To better understand head lice, how they spread, and what you can do to prevent them, our Lice Facts page is a comprehensive resource filled with essential information, practical tips, and expert advice to help you stay ahead of lice infestations. Whether you’re dealing with lice now or want to be prepared for the future, our Lice Facts page is a great place to start. Empower yourself with the knowledge to keep your family lice-free!
Lice Facts
LICE
Although there are many types of lice, the head louse, or Pediculus humanus capitis, is a parasitic insect that can be found on the head and, more rarely, the eyebrows and eyelashes of people. Head lice (the plural form of louse) feed on human blood several times a day and live close to the scalp to maintain their body temperature.
LIFE CYCLE
Head lice come in three stages: egg, nymph and adult (learn how big lice are in their various stages).
Eggs are often called lice nits, although many people refer to nits as the empty egg shells left behind by a hatched louse.
LICE HAVE CLAWS
A head louse has six claws that allow it to crawl around from hair strand to hair strand.
This way, it can move from one head to another, which is why head-to-head contact is the primary way head lice are spread between people.
HEAD TO HEAD
A head-lice infestation occurs when a female adult louse makes it onto a new head and lays eggs. When those eggs hatch, the lice will most likely stay on that head throughout the entire lice life cycle. Unless the head is treated (see pediculosis treatment) and all lice and eggs are eradicated, the lice infestation will continue for however long the lice can live.
Lice FAQs
Adult lice will be the easiest to spot because they are the biggest. But at the size of a sesame seed, they still aren’t that big. Although lice vary in color, if you see a grayish-white or tan bug crawling through the hair, it is probably a louse. If you look closely at an adult louse, you should be able to see human blood inside it.
Look at the hair strands about a quarter inch (~0.5 cm) off the scalp. See if you can find lice eggs (often called nits) attached to individual hairs. Nits are extremely small. They look like tiny specks and will be glued pretty securely to the hair. If you see any, try pulling them off with your fingers. If you can’t easily pull them off, they are probably eggs and not dandruff.
The primary way you can get head lice is when your head comes in direct contact with the head of an infested individual. Head-to-head contact like that doesn’t guarantee that the infestation will spread, but it gives lice the best opportunity to move from the hair of the infested person to your hair.
Head lice don’t jump, swim or fly. Without strands of hair to grab with the claws on their legs, they have trouble getting around at all. However, they can crawl pretty quickly along the hair, so if your hair comes in contact with an infested head, it doesn’t take much for a louse to hitch a ride on a strand of your hair and make its way to your scalp.
Excluding the 8-9 days they spend as eggs, head lice can live for around 40-45 days on your head. As parasites, they feed on human blood several times a day.
If they are removed from their food source – say from getting knocked out of your hair with a brush or your hand – they can survive 24-48 hours. If they don’t find some human hair to crawl back to a new host during that time, they will die.
Head lice do not survive long if they fall off a person and cannot feed. You don’t need to spend a lot of time or money on housecleaning activities. Follow these steps to help avoid re–infestation by lice that have recently fallen off the hair or crawled onto clothing or furniture.
- Machine wash and dry clothing, bed linens, and other items that the infested person wore or used during the 2 days before treatment using the hot water (130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry–cleaned OR sealed in a plastic bag and stored for 2 weeks.
- Soak combs and brushes in hot water (at least 130°F) for 5–10 minutes.
- Vacuum the floor and furniture, particularly where the infested person sat or lay. However, the risk of getting infested by a louse that has fallen onto a rug or carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. 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; they can be toxic if inhaled or absorbed through the skin.