Head Lice

Head lice is an infestation of tiny, parasitic insects most often found behind the ears and at the back of the neck. Though concerning, lice infestation is not a health hazard—head lice are not responsible for the spread of any disease. 

The main symptom of a lice infection is the feeling of something moving around in your hair. As lice are most active at night, this can lead to trouble sleeping. Itching may set in after a few weeks and is caused by an allergic reaction to the louse's saliva. Scratching can lead to a secondary infection, resulting in sores on the scalp. 

Over-the-counter treatments and diligent combing to remove lice and eggs (nits) are usually effective. 

There are 6 to 12 million cases of head lice in the United States every year among children 3 to 11 years of age. Head lice occur more often in children than in adults.

Frequently Asked Questions

  • How can you get rid of head lice?

    The first line of treatment for head lice is an over-the-counter anti-lice shampoo, which kills adult lice and nymphs (young lice), but not nits (eggs). Follow-up treatment may need to be applied seven to 10 days after the initial treatment. Additionally, wet-combing using a fine-toothed lice comb is also recommended to remove lice and nits.

  • What causes head lice?

    Head lice is caused by simple head-to-head contact, or when your head touches another person's head who has a lice infestation. Because young children often play closely together, lice outbreaks are often seen in preschools, daycares, and overnight camps. However, lice can spread to people of any age. It's possible that lice are also spread via items like hats or brushes but this is much less common.

  • How can you check for head lice?

    Look for head lice at home in a bright room with a magnifying glass and a lice comb. Live lice can move quickly and try to avoid light. Be sure to look closely at the scalp, around the ears, and the back of the neck, near the hairline. An adult louse is about the size of a sesame seed. If lice are found on one person in your household, all members of your household should be checked.

  • Can head lice jump?

    No, head lice move by crawling—they cannot hop, jump, or fly.1 Lice are spread by direct contact with the head of another person. They may also be spread through bedding or clothes, but this is much less common.

  • How long do head lice live?

    An adult louse can live for about 30 days on a person's scalp, but will die in one to two days if it falls off a person.1 Lice develop in three phases: nit (egg), nymph (young adult), and adult louse.

  • How long will your head be itchy after lice are gone?

    Even after lice treatment and removal, your scalp may still itch for a week or more after lice are gone. This is due to the allergic reaction caused by the louse saliva on your scalp.

Key Terms

Page Sources
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  1. Meister L, Ochsendorf F. Head lice: Epidemiology, biology, diagnosis, and treatment. Deutsches Ärzteblatt International. 2016;113(45):763-772. doi:10.3238/arztebl.2016.0763

  2. Centers for Disease Control and Prevention. Head Lice: Frequently Asked Questions (FAQs). Updated July 17, 2019.

Additional Reading