Head Lice

Medically reviewed by Lyndsey Garbi, MD
Updated on February 27, 2025

Head lice is an infestation of tiny, parasitic insects most often found behind the ears and at the back of the neck. 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. Over-the-counter treatments and diligent combing to remove lice and eggs (nits) are usually effective.

Understanding Head Lice

A woman checking a child's hair for lice
Head Lice: Their Life Cycle, Their Treatment, and Prevention
Louse egg on the hair causes itchy head.
Could You Spot Head Lice in a Picture?
Mother combs her daughter's hair to check for lice
Smart Ways to Prevent Kids From Getting Head Lice
Young boy scratching head
Lice Symptoms You Need to Be Aware Of
Mother Doing Head Lice Inspection On Daughter to determine how to treat it
How to Get Rid of Lice ASAP

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.

    Learn More: How Head Lice Is Treated
  • 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.

    Learn More: Causes and Risk Factors of Head Lice
  • 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.

    Learn More: Causes and Risk Factors of Head Lice
  • 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

  • Dandruff

    Dandruff is a skin condition primarily affecting the scalp, marked by the appearance of flakes of dry skin. Dandruff flakes may be confused for nits, but flakes can be easily moved along the hair shaft and aren't uniform in size, unlike lice nits, which are firmly attached to the hair shaft close to the skull, and are small and oval-shaped.

    How Head Lice Is Diagnosed
  • Lice Nits

    The egg phase of a louse life cycle. Nits are typically attached firmly to the hair shaft no more than ¼ inch away from the scalp. Nits hatch every eight to nine days and are oval-shaped, yellow-white, and very small.

    What Do Head Lice Look Like?
  • Pediculus

    Pediculus is the genus of the lice organism. An infestation of head lice is called pediculosis.

  • Scalp

    The skin covering your head (excluding your face), where hair typically grows. Lice live close to the scalp and feed on human blood several times per day.

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

Additional Reading