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Head lice - Overview

Alternative Names

Lice - head; Nits; Pediculosis capitis - head lice

Definition of Head lice:

Head lice are tiny insects that live on the skin covering the top of your head, called the scalp. Lice can be spread by close contact with other people.

Head lice may also be found in eyebrows and eyelashes.

Causes, incidence, and risk factors:

Head lice infect hair on the head. Tiny eggs on the hair look like flakes of dandruff. However, instead of flaking off the scalp, they stay put.

Head lice can live up to 30 days on a human. Their eggs can live for more than 2 weeks.

Head lice spread easily, particularly among school children. Head lice are more common in close, overcrowded living conditions.

You can get head lice if you:

Come in close contact with a person who has lice
Touch the clothing or bedding of someone who has lice
Share hats, towels, brushes, or combs of someone who has had lice

Having head lice does NOT mean the person has poor hygiene or low social status.

Having head lice causes intense itching, but does not lead to serious medical problems. Unlike body lice, head lice never carry or spread diseases.

Head lice

Nit on human hair

Lice, head - nits in the hair with close-up

Head louse emerging from egg

Head louse, male

Head louse - female

Head louse infestation - scalp

Reviewed last on: 1/24/2011
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

Morelli JG. Arthropod bites and infestations. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Nelson Textbook of Pediatrics. Philadelphia, Pa: Saunders Elsevier; 2007:chap 667.

Schlossberg D. Arthropods and leeches. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 380.

Diaz JH. Lice (pediculosis). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 293.

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