Nit comb, medicinal shampoo are effective in treating lice

DEAR DOCTOR K: A child in my daughter’s classroom has head lice. What do I need to do if my daughter gets it?

DEAR READER: Lice – the visitor dreaded by parents everywhere.

Head lice are small insects that infest hair on people’s heads. A single insect is called a “louse.” The female lays up to 100 eggs, or nits, at a time. She secretes a kind of glue that attaches the nits onto strands of hair near the scalp. Once the eggs hatch, their six legs allow them to grasp and wander between hairs. In their remaining days or weeks of life, they feed on human blood. They’re sort of like vampires, only much smaller. (I’ve put an illustration of a louse on my website, AskDoctorK.com.)

You’ll know to check your daughter for lice if she is scratching her head often. If you think your daughter has them, you may want to check in with her pediatrician. Lice and their eggs are often hard to see or distinguish from dandruff or other material caught in the hair.

With proper treatment, head lice usually go away within about two weeks. One option is to use a special louse comb or nit comb to remove lice and their eggs from your daughter’s hair. This sometimes requires combing several times a week until no lice are seen for two or more weeks. It is possible through careful combing to remove all of the lice, without using medicines to kill them.

Your pediatrician may prescribe a medicine called a pediculicide. They are special insecticide products that are available over the counter and by prescription in drugstores. Do not apply any other kind of insecticide to your daughter’s body or hair; other insecticides can be toxic if applied to the skin.

Most pediculicides contain chemicals called pyrethroids as the active ingredient. These usually are applied as a shampoo, then washed off about 10 minutes later. A second treatment is often necessary about 10 days later. When you wash off the pediculicides from your daughter’s hair, do it over the sink, not in a shower or tub. That’s because you want to minimize splashing the pediculicide on skin outside the head. It’s easier to control where the rinse water goes in the sink.

Head lice are acquired by direct contact with an infested person’s hair. It’s unusual for head lice to be transferred by shared combs, brushes, hats or other hair accessories. Head lice are also not usually found on clothes, towels and bed linens. Still, you may want to change any items that were recently in direct contact with your daughter’s hair and wash them in hot water.

Head lice do not transmit infections. In other words, they are not like the ticks or mosquitos which carry bacteria or viruses that can infect humans.

Finally, despite what many people believe, head lice are neither caused by, nor are a sign of, poor hygiene or housekeeping. They’re just something a person (usually a child) can pick up – and something you can cure.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.