Head Lice (pediculosis)

As school begins, parents may be concerned about the threat of head lice spreading amongst the children. Learn more about this nuisance that can occur to anyone in close quarters, but does not spread disease. 

 What is head lice (pediculosis)?

Pediculosis is an infestation of head lice on the hair of the head. The lice feed on human blood that can cause severe local itching, especially around the back of the head and ears. Head lice are frequently found in schools and day care centers and are easily spread from person-to-person.

Prevention & Control
Head lice are spread most commonly by direct head-to-head (hair-to-hair) contact. However, much less frequently they are spread by sharing clothing or belongings (such as combs, brushes, and hats) onto which lice have crawled or nits attached to shed hairs may have fallen. The risk of getting infested by a louse that has fallen onto a carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the scalp. 

The following are steps that can be taken to help prevent and control the spread of head lice:

  • Avoid head-to-head (hair-to-hair) contact during play and other activities at home, school, and elsewhere (sports activities, playground, slumber parties, camp).
  • Do not share clothing such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
  • Do not share combs, brushes, or towels. Disinfest combs and brushes used by an infested person by soaking them in hot water (at least 130°F) for 5–10 minutes.
  • Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.
  • Machine wash and dry clothing, bed linens, and other items that an infested person wore or used during the 2 days before treatment using the hot water (130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry-cleaned OR sealed in a plastic bag and stored for 2 weeks.
  • Vacuum the floor and furniture, particularly where the infested person sat or lay. However, spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice or nits that may have fallen off the head or crawled onto furniture or clothing.
  • Do not use fumigant sprays or fogs; they are not necessary to control head lice and can be toxic if inhaled or absorbed through the skin.

What is the treatment for head lice?

There are several medicated shampoos commonly used to treat head lice. Shampoos or creme rinses that contain 1% permethrin have the fastest killing time against adult lice and the highest nit-killing capability. Permethrin has a residual effect that will continue to kill nits for several days after the first application. While one application should be sufficient to kill lice and nits, some experts suggest a second treatment one week after the first.

Shampoos that contain pyrethrin (natural pyrethroid from chrysanthemums) kill lice quickly but do not leave a residual that will continue to kill nits, resulting in a less effective treatment. Two applications of these types of shampoo 7-10 days apart are recommended to kill nits. Shampoos containing malathion and lindane are available by prescription only, if OTC treatments do not work.

DO NOT use a combination shampoo/conditioner or conditioner before using the lice medicine and do not re-wash the hair for 1-2 days after the lice medicine is removed. Do not use a shower cap with the medications. Comb out lice and nits with a fine-toothed comb. Nits more than a ¼ inch above the scalp are usually not viable.

Alternate treatment methods such as the use of tub butter or margarine, mayonnaise, Vaseline® and olive oil, designed to smother head lice and nits can be used optionally for those persons for whom lice-killing medications have failed. Apply overnight, using a shower cap with discretion for older children and adults only. The effectiveness of alternative treatments is unclear. To aid in the removal of nits, hair can be wrapped in a 3-5% white vinegar soaked towel for 30-60 minutes before nit removal.

For more information

Go to the Wisconsin Department of Health's head lice guide (PDF) or the head lice information for parents from the Center for Disease Control.