Head Lice Infestation
Head lice are small, wingless, blood-sucking insects that live in the hair on your head and feed off the blood from your scalp.

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What Are Head Lice?

Head lice are small, wingless, blood-sucking insects. They live in the hair on your head and feed off the blood from your scalp. A louse (a single adult) is about the size of a sesame seed. A nit (louse egg) is about the size of a flake of dandruff.

What Causes Head Lice?

Head lice are contagious. You can become infected with head lice when the insects crawl onto your head. Ways you might get head lice include:

  • touching your head to an infected person’s head
  • sharing the personal items of someone with head lice
  • using a fabric item after an infected person

Lice can be transferred by brushes, combs, barrettes, headbands, headphones, and hats. They can also live for a time on upholstered furniture, bedding, towels, or clothing.

Who Is at Risk for Head Lice?

Preschool and elementary school students have the highest risk of getting head lice. They tend to play close together and share items which touch their heads. There is also an increased risk of head lice for family members of school aged children. People who work in a daycare, preschool, or elementary school share this risk.

What Are the Symptoms of Head Lice?

Symptoms of head lice include:

  • extreme scalp itchiness
  • feeling like something is crawling on your scalp
  • sores on your scalp from scratching

How Are Head Lice Diagnosed?

You or your healthcare provider can diagnose head lice by:

  • checking your hair, close to the scalp, for lice
  • checking your hair, close to the scalp, for nits
  • running a fine-toothed lice comb through your hair, starting from the scalp, to catch lice and nits

You can differentiate between nits and dandruff flakes by seeing if white flakes stick to hair. If they do, they’re probably nits. Dandruff is easy to remove.

Head lice are contagious. If one person in your household has them, others may too. It’s a good idea to check everyone for signs of lice every few days.

How Are Head Lice Treated?

There are several head lice treatments available. Most treatments will need to be used twice. The second treatment, after a week to nine days, will kill any newly hatched nits.

Some of the major treatments for head lice are described below.

Medications

There are both over-the-counter (OTC) and prescription head lice treatments.

Two types of chemicals are commonly used in OTC head lice treatment.

Pyrethrin is a pesticide that comes from chrysanthemum flowers. It is approved for use in people 2 years old and older. Do not use pyrethrin if you are allergic to chrysanthemums or ragweed.

Permethrin (Nix) is a synthetic pesticide that is similar to pyrethrin. It is approved for use in people 2 months old and older.

Prescription lice treatments may also include other chemicals.

Benzyl alcohol lotion (Ulesfia) is an aromatic alcohol. It is used to treat head lice in people 6 months old and older.

Malathion (Ovide) is an organophosphate pesticide. It is used to treat lice in people who are 6 years old or older. It is not recommended for women who are pregnant or breastfeeding. Malathion is flammable. Stay away from open flames and heat sources such as hair dryers when using this product.

Lindane is an organochloride pesticide. It is available in lotion or shampoo form. Lindane is usually only used as a last resort. It can cause serious side effects, including seizures and death. Lindane should not be used by premature babies or by people who have a history of seizures.

In order to reduce the risk of side effects:

  • Do not use more than one medication.
  • Do not use any medication more often than directed.

Alternative Treatment

If you want to avoid using pesticides, use a fine-toothed lice comb or a flea comb (sold in pet stores) to remove lice. Apply olive oil to your hair before combing. This will help the lice and nits stick to the comb. Start combing at the scalp and work through the end of the hair.

You will need to do this every two to three days until you have no more signs of lice or nits.

Treating Your Home

There is no need to use pesticides around your home. Lice cannot survive more than a couple of days off your head. The following methods can be used to kill lice on different items:

  • wash clothes and bedding in hot water (130 degrees Fahrenheit or above) and dry on high heat in the dryer
  • dry clean clothes and bedding
  • seal clothes, bedding, and plush toys in a plastic bag for two weeks
  • soak hair brushes, combs, barrettes, and other hair accessories in hot water (130 degrees Fahrenheit) for five to 10 minutes
  • vacuum floors and upholstered furniture

Long-Term Outlook

You can get rid of head lice with the proper treatment. However, you may become re-infected. Reduce that risk by cleaning your house properly and avoiding contact with other infected people until they have been treated.

Preventing Head Lice

You can reduce your chances of getting head lice by not sharing personal hygienic items with others.

Written by: Rose Kivi and Elizabeth Boskey, PhD
Edited by:
Medically Reviewed by: George Krucik, MD
Published: Aug 16, 2012
Published By: Healthline Networks, Inc.
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