Head Lice (Pediculosis)
(peh-DICK-you-LO-sis)
An adult head louse. (CDC Photo)
Adult head lice are 2.1-3.3 mm in length. Head lice infest the head and neck and attach their eggs to the base of the hair shaft. Lice move by crawling; they cannot hop or fly.
Head lice infestations are spread most commonly by close person-to-person contact. Dogs, cats, and other pets do not play a role in the transmission of human lice.
Both over-the-counter and prescription medications are available for treatment of head lice infestations.
Specific Topics
Information for Special Groups and Settings
Head Lice Resources
Page last reviewed: May 16, 2008
Content Source: Division of Parasitic Diseases (DPD)
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)