March 15, 2013
Head lice are very small insects that live on the scalp. They bite the scalp often causing intense itching. It is also possible to find head lice in eyebrows and eyelashes. Lice can be spread by close contact with infected people.
Causes, incidence, and risk factors
Head lice infect hair on the head. Tiny head lice eggs on the hair resemble the appearance of dandruff flakes. Unlike dandruff that flakes off, the eggs remain attached to the hair.
On a human, the life span of head lice can be up to 30 days. The eggs can live for more than several weeks.
Head lice spreads easily, especially among children. It is more common for Head lice to occur in close, overcrowded living conditions.
You can get head lice if you:
- Come in close contact with a person who has lice
- Touch the bedding, clothing, or other articles of someone who has the lice
- Share hats, towels, brushes, or combs of someone who has had lice
Being infected with head lice does NOT mean the person has poor hygiene or low social status.
Having head lice may cause intense itching, but it does create more serious medical issues. Unlike body lice, head lice never carries or spreads disease.
Signs and tests
Head lice can be difficult to see. You need to examine the hair and scalp very closely. It is critical to use disposable gloves and look at the person’s head under a bright light. Performing an examination under the full sun or the brightest lights in your home during daylight hours is the best time. Using a magnifying glass can also help one view the tiny head lice.
Part the hair all the way down to the scalp in very small sections, looking both for moving lice and eggs (nits). Examine the entire head this way. Look very closely around the top of the neck and ears which are the most common locations for the eggs to be deposited.
Even if one egg is found then treatment is recommended.
Lotions and shampoos containing 1% permethrin (Nix) often work well. They can be purchased without a prescription. If these do not work, a doctor can give you a prescription for stronger medicine.
Ask your health care provider if you need to treat those who shared a bed or clothing with the person that has had lice.
Malathion 0.5% in isopropanol is FDA approved for the treatment of head lice. Apply it to dry hair until the hair and scalp are wet. Leave it on for 12 hours. Malathion may be useful for resistant infections.
Lice are usually killed with proper treatment. However, lice may come back, especially if the source is not corrected. For example, a classroom with many infected children can cause kids to repeatedly get lice.
When one case is detected in a family or a school or child-care center, every child at that location should be examined for head lice. This can help prevent further spreading.
Calling your health care provider
Call your health care provider if symptoms continue after home treatment, or if you develop areas of red, tender skin, which could mean a possible infection.
Never share hair brushes, combs, hair pieces, hats, bedding, towels, or clothing with someone who has head lice.
If your child has lice, be sure to check policies at schools, day-care centers, preschools, and nurseries. Many do not allow infected children to be at school until the lice have been completely treated.
Some schools may have policies to make sure the environment is clear of lice. Sometimes, the insects or their eggs get into areas such as carpets. Frequent cleaning of carpets and all other surfaces in child-care centers prevents spread of all types of infections, including head lice.