Lice are tiny insects that attach to human hair and feed on very small amounts of blood they draw from the scalp. Once they start living in hair, lice lay eggs (called nits) close to the scalp. Lice can survive for up to a month on a person’s head and can lay up to eight eggs a day.
Lice aren’t dangerous and they don’t carry any diseases, but their bites can cause severe itching and irritation of the scalp.
Lice can spread from person to person by close contact or through shared items such as hats, hairbrushes, pillowcases and clothing. Lice are very common in preschool and elementary school-aged children, since they play together closely and often share more of these items than adults do.
Lice: Reviewed by Claire McCarthy, MD
© Boston Children’s Hospital, 2012