What are head lice?
Head lice are tiny crawling insects that live in a person’s head hair. The lice feed on blood sucked from the scalp and lay eggs — called nits — that firmly attach to the hair shafts. Infestation with head lice is also called pediculosis.
How common are head lice?
Head lice infestation is common, affecting 6 million to 12 million people each year. Lice are most common in school children, who are more likely to have close contact and to share combs, brushes and other objects. Head lice are more common in girls than in boys and are more common in Caucasians than in African-Americans. Anyone can get head lice. It is not a sign that a person is unclean.
Symptoms and Causes
How does a person get head lice?
Head lice spread by direct head to head contact and by sharing items — including combs, brushes, scarves and hats — with an infected person.
What are the symptoms of head lice?
The most common symptom of head lice is itching, especially in the back of the head and neck and near the ears — areas where lice are more likely to live. Intense scratching can break the skin of the scalp and can lead to open sores and infection. However, it may take as long as two to three weeks after lice infestation for itching to begin.
Diagnosis and Tests
How are head lice found?
If you look closely, you may be able to see the tiny nits attached to the hair shafts. Nits resemble dandruff but are not as easy to brush or shake off of the hair. Adult lice can move around quickly and are, therefore, difficult to see.
Management and Treatment
How are head lice treated?
Special medicated shampoos and hair-rinses that contain a substance called pyrethroids are available without a prescription to kill the lice and nits. Using a fine-toothed comb can help loosen the nits from the hair. It is important to also wash all combs, brushes, hats and towels after each shampoo.
Make sure you follow the directions on the over-the-counter medicine. Many times, the treatments don’t work well because many people don’t use them as directed. Be sure to apply a second treatment about a week later. This second treatment is necessary to kill the survivors of the first application. Keep the medicine on your scalp long enough, or it may not be effective.
Treating resistant "super lice"
Over the years, some lice (so-called "super lice") have evolved so that pyrethroids no longer connect neatly with the receptors, reducing the chemical’s ability to kill the insect. Powerful prescription drugs like ivermectin (brand name Sklice®) are available that can eliminate super lice with one dose.
Can head lice be prevented?
The best prevention is to not share combs, brushes, towels or hats with others and to avoid physical contact with someone who has lice. It also helps to examine and treat all members of your household who have had contact with a person with lice.
Children who have head lice do not have to stay home from school. Tell the school, day care center, or baby sitter if your child has head lice. The other children can be checked and treated, too, if necessary.
When should I call my health care provider about head lice?
Call your health care provider if over-the-counter treatments fail to work or if there are signs of an infection. Signs of infection include fever; sores that won’t heal; and pain, tenderness, redness or swelling.