Scratch scratch. Scratch. Your head is feeling really itchy. Could it be lice?

If so, you're not alone. Every year, between 6 and 12 million people worldwide get head lice. Most of those millions are kids. Any kid who goes to school has probably already heard about lice. They can spread easily at schools, so if one kid gets them, the rest of the class might get them, too. What can you do? Let's find out.

What Are Lice?

Lice are very, very small insects. In fact, they are so tiny that you can barely see them! Each louse (the name for one of the lice) is brown and gray and only about the size of a sesame seed.

Lice are parasites (say: pah-ruh-sytes), which means that they live off other living things. Head lice need to be next to skin to survive - and the warmth of your skin is a perfect place for them to live. Lice eat tiny amounts of blood (much less than a mosquito does) for their nourishment and use their sticky little feet to hold on to hair. Gross!

When lice start living in hair, they also start to lay eggs, or nits. Lice can survive up to 30 days on a person's head and can lay eight eggs a day. Lice attach their nits to pieces of hair, close to the scalp. If you see a small, oval blob on a strand of hair, that's probably a nit. If these little eggs are yellow, tan, or brown, the lice haven't hatched yet. If the eggs are white or clear, the lice have hatched.

Although they don't hurt, lice sometimes can irritate the skin and make it itchy (especially at night). Too much scratching can lead to scalp infections.

Lice Love Everyone

Because lice are parasites, they will set up house on anyone's head, whether that person is clean, dirty, in second grade, in fifth grade, black, or white. Anyone who says that people who get lice are dirty doesn't know that lice love everyone and that includes the cleanest kid in the class! Lice spread in classrooms and schools because kids play together closely and often share more stuff than adults do.

Lice cannot jump or fly. They spread when people's heads touch or when they share hats and other clothing, combs, brushes, headbands, barrettes, and bedding (like sheets, blankets, pillowcases, and sleeping bags). If lice are stuck on any of these things and that thing touches another person's head, that person may also get lice.

Saying Goodbye to Lice

If your head feels very itchy, tell an adult as soon as possible. This is especially true if you know that other kids in your class or school have had lice. Don't wait around — the more time the lice have to lay nits, the itchier you will be!

Often a parent or school nurse can recognize head lice just by looking for nits in the hair. Some kids' parents will take them to the doctor so the doctor can check to see if lice are there.

If a kid has lice, an adult will need to buy a special medicated shampoo, cream, or lotion that kills lice. An adult will need to apply the medicine and follow the directions. Part of the treatment is combing your hair with a fine-tooth comb to remove the nits. The shampoo, cream, or lotion usually kills the lice right away. The itching should go away within a few days, but treatment may need to be repeated in 7 to 10 days to kill any new lice that may have hatched since the first treatment.

Do not use a hair dryer on your hair after washing with the medicated shampoo, lotion, or cream because they can contain flammable ingredients. You don't want your hair catching on fire.

Although lice can live for only 1 to 2 days off a person's head, it's a good idea for an adult to wash all your bedding, hats, clothing, and stuffed animals in hot water. Or he or she can seal these things in airtight bags for 10 days. That also will kill the lice and their eggs.

Vacuuming the carpets, upholstery, and car seats will take care of any lice that fell off before treatment. Combs, brushes, and hair accessories need to be soaked in hot water, washed with medicated shampoo, or thrown away. Sometimes it is difficult to get rid of the lice, so if that happens to you, have your parent talk to the doctor. There are stronger medicines and other treatments that they may decide to use.

Life Without Lice

Sure, lice aren't so nice, but there are things you can do to keep them away. To help prevent lice:

• If your friend has lice, don't give the lice any chance to spread to you. Avoid putting your heads together or sharing stuff that could contain lice, such as hats or combs.
• Don't try on hats that belong to other kids.
• Never share a comb, brush, barrettes, or other hair accessories. Use your own, and don't lend them to anyone else.
• Always use your own sleeping bag and pillow when sleeping away from home.

Sharing is usually a great idea — except when you're sharing lice!

Reviewed by: Steven Dowshen, MD
Date reviewed: July 2010