Lice are tiny insects that live on humans and survive by feeding on blood. Although they cannot jump or fly, they spread easily from one person to another through close contact or shared personal items.

Head lice, pubic lice, and body lice are the three main types that live on humans. When a large number of lice collect and reproduce on a person's body, it is called an infestation. Lice can infest people from all races and socioeconomic backgrounds.

The main symptom of lice infestation (pediculosis) is itching in the affected areas. The nits (eggs) of hair and pubic lice may be seen on hair shafts, while nits of body lice are most often found in the seams of clothing. Scratching affected areas can make the skin raw, and these areas may become infected. Bites from pubic lice can cause small bruiselike marks on the torso, thighs, or upper arms.

Treatment usually begins with application of a cream, shampoo, or lotion to kill lice. Prescription and nonprescription medications are both available. Washing clothes and linens in hot water is generally recommended.