What are lice?

Lice are tiny wingless insects. They are 1 to 3 millimeters long, or less than 1/8 inch. There are several types of lice, including some that look like tiny crabs and are called crab lice.

Lice live on humans and animals, usually in the hairy parts of the body. They bite through the skin to suck blood. The bites can cause itching and sometimes skin irritation. The lice attach their eggs, called nits, to the hairs in the scalp, eyelashes, underarms, and pubic area. The nits hatch in 8 to 10 days, producing more lice.

How do people get lice?

You can get lice by coming into contact with living lice or their eggs. This may occur with close sexual contact or from sharing personal items such as combs, brushes, and hats. Head lice may live on items such as clothing, bedding, and towels up to 3 days. Crab lice can live up to 1 to 2 weeks on such items.

What are the symptoms?

Sometimes lice do not cause any symptoms. Most often, however, you have some itching or you may see one or more lice. Sometimes you may see the nits. The nits look like tiny white dots attached firmly to a hair. They look like dandruff. Dandruff, however, is easily brushed out of the hair. Nits cannot be brushed or flicked off. They must be pulled off the hair with your fingers.

How is it diagnosed?

Your health care provider looks for lice or nits in your hair.

How is it treated?

Nonprescription products, such as Nix, can be used to kill lice and nits. If a nonprescription product does not kill the lice, your health care provider may prescribe a shampoo or lotion containing the medicine lindane. However, the nonprescription medicines are safer for preschool children than lindane. Lindane can cause seizures if it is not used correctly. Carefully follow the directions for its use, and do not overuse it.

If you are pregnant, check with your health care provider before you use any type of anti-lice shampoo.

When you use an antilice shampoo, lather the shampoo into the area where the lice are. Leave the shampoo on for several minutes, then thoroughly rinse it out. One treatment is usually enough, but your health care provider may recommend that you repeat the shampooing in 1 week.

If the lice are in your eyebrows or eyelashes, you will probably need to remove them carefully with your fingers. In some cases, medicine that is safe for the eyes can be used.

After treatment with antilice medicine, the dead nits will still be on the hairs. You must remove all of them. Otherwise, if you see nits several days after your treatment, you will not know if they are old dead nits or a new infestation. Use a fine-tooth comb, tweezers, or your fingers to remove the dead nits.

As important as the treatment of the hair and skin is the treatment of your environment, which you must rid of remaining lice. All clothing, bedding, and towels must be laundered. Sometimes people are advised to buy a special lice insecticide spray to use on furniture. However, careful vacuuming may be as effective in most cases.

What can be done to help prevent lice?

The best way to prevent lice in the genital area is to have one monogamous partner or avoid intimate sexual contact. Condoms are not good protection against lice because they do not cover the hairy areas where the lice live. You should also avoid contact with contaminated clothing, bed clothing, and toilet seats.

Prevention of head lice is more difficult, especially among children. Lice can move from person to person from close contact during play. They can get on hats, hooded coats, scarves, combs, brushes, pillows, and cuddly toys. To help prevent lice, do not share these items.

Because it is so difficult to prevent the spread of lice among preschool and school-age children, lice should not be seen as a sign of poor hygiene or failure by parents. The problem should just be dealt with in a calm, practical manner.