Head Lice (Pediculosis Capitis)
Head lice are small insects (less than 1/8 inch long, approximately the size of a sesame seed). Head lice live on blood they draw from the scalp and lay tiny, gray/white eggs (known as nits) near the scalp. The warmth from the scalp is needed for the eggs to hatch. Head lice are not known to spread disease.
Transmission
Head lice can affect anyone and can spread as long as lice or eggs remain alive on the infested person or clothing. In the United States, head lice are most common among preschool children attending child care, elementary school children, and household members of infested children. Head lice are commonly spread via:
- Person to Person by direct contact with hair.
- Environment to Person. By sharing combs, brushes, hats, blankets, or sheets with others, this is less common. Head lice can only be spread by live lice and not nits.
A person who previously had head lice may get it again.
Symptoms
For many people, head lice cause no symptoms. The time from laying eggs to hatching is about one week (six to nine days). Lice mature to the adult stage approximately seven days later. When symptoms are present, they include:
- Itching is one of the most common symptoms. Itching is often located on the skin on the scalp or neck.
- Small red sores on the scalp may be seen due to bites from the louse and continued itching.
- Tickling feeling of something moving in the hair some people report a crawling feeling in the hair.
- Sleeplessness lice are more active at night and may disrupt sleep.
Diagnosis
Diagnosing head lice is done by identifying live lice or nits within 1/4 inch of the scalp. Eggs and lice can be seen with the naked eye; however, the use of a hand lens or microscope may help to confirm the identification.
Treatment
- Medicated shampoos or cream rinses containing lindane or pyrethrins.
- Over-the-counter products containing pyrethrins.
- Prescribed medication containing lindane or pyrethrin.
- Lindane is not recommended for infants, young children, and pregnant or lactating women.
- Nit combs remove lice eggs from hair and are more useful than medications on eggs.
Dose and duration of shampoo treatment should be followed according to label instructions. Extra amounts should not be used, and multiple products should not be used at the same time. Retreatment after seven to ten days is recommended to assure that no eggs have survived.
For more information about the treatment of head lice, contact your health care provider or visit Treatment of Head Lice | Lice | CDC.
Prevention
- Avoid physical contact with infested individuals and their belongings, especially clothing, headgear and bedding.
- Examine close contacts and playmates of infected persons.
- Educate on the life cycle of lice, proper treatment, and the importance of laundering clothing and bedding in hot water (130°F for 20 minutes) or dry cleaning to destroy lice and eggs.
- Inspect regularly for lice, on the scalp (and when indicated on the body and clothing), particularly of children in schools, and persons in institutions, nursing homes, and summer camps, is important.
Exclusion Guidance
Individuals with head lice should not be excluded from work, school, or childcare unless the general exclusions apply.
- Exclusion and treatment of children in school and child care can occur at the end of the day with return the following day after their first treatment.
- Head-to-head contact with others should be discouraged.