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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 small flake of dandruff.
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 the head of someone with head lice
- sharing the personal items (e.g., comb) of someone with head lice
- using a fabric item after a person with head lice
While transmission of lice via inanimate objects may be possible, it’s been found to be highly unlikely. Some of these inanimate objects may include brushes, combs, barrettes, headbands, headphones, and hats.
It may also be possible for lice to live for a time on upholstered furniture, bedding, towels, or clothing.
Again, it should be stressed that the biggest concern for transmission is close head-to-head contact occurring mainly in children during play. Transmission via objects is a rare exception, according to several sources.
There are some differing opinions on the transmission of head lice via inanimate objects, but the science doesn’t seem to support transmission in this manner.
Preschool and elementary school students have the highest risk of getting head lice. They tend to play closely together.
There’s also an increased risk of head lice for family members of school-aged children. People who work in a day care center, preschool, or elementary school share this risk.
Symptoms of head lice include:
- extreme scalp itchiness
- feeling like something is crawling on your scalp
- sores and scabs on your scalp from scratching
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
The nits are dark-colored, and hatched lice will be light-colored.
Adult lice move quickly. You’ll most likely find nits if you find any evidence of head lice on your scalp.
You can easily differentiate between nits and dandruff flakes or other debris in your hair. Most debris should be removed easily. Nits will seem like they’re cemented to your hair.
Head lice are contagious. If one person in your household has them, others may too. It’s a good idea to check everyone in the household for signs of lice every few days.
There are several head lice treatments available. Most treatments will need to be used twice. The second treatment, after a week to 9 days, will kill any newly hatched nits.
Some of the major treatments for head lice are described below.
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’s derived from chrysanthemum flowers. It’s approved for use in people 2 years old and older. Don’t use pyrethrin if you’re allergic to chrysanthemums or ragweed.
Permethrin (Nix) is a synthetic pesticide that’s similar to pyrethrin. It’s 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’s used to treat head lice in people 6 months old and older.
Malathion (Ovide) is an organophosphate pesticide. It’s used to treat lice in people who are 6 years old or older. It isn’t 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’s available in lotion or shampoo forms. Lindane is usually only used as a last resort. It can cause serious side effects, including seizures and death. Lindane shouldn’t be used by premature babies or by people who have a history of seizures.
In order to reduce the risk of side effects:
- Don’t use more than one medication.
- Don’t use any medication more often than directed.
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’ll need to do this every 2 to 3 days until you have no more signs of lice or nits.
Treating your home
There’s no need to use pesticides around your home. Lice can’t 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°F (54°C) or above — and dry on high heat.
- Dry-clean clothes and bedding.
- Soak hair brushes, combs, barrettes, and other hair accessories in hot water — 130°F (54°C) — for 5 to 10 minutes.
- Vacuum floors and upholstered furniture.
You can get rid of head lice with the proper treatment. However, you may become reinfected. Reduce that risk by cleaning your house properly and primarily avoiding head-to-head contact with people who have head lice until they’ve been treated.
It may be prudent to not share personal hygiene items with others to reduce your chances of getting head lice, although current evidence doesn’t necessarily support this thought.