Head Lice Patient Information Fact Sheet

What are head lice?
Head lice are tiny, wingless insects that remain smaller than a match head when fully grown. They are grey/brown in color and very difficult to see, particularly in dry hair. Head lice infestation is more common in children than in adults. Infestation with head lice is also known as pediculosis.

The presence of head lice does not indicate a lack of good hygiene. They will infest any type of hair but tend to be more common in people with long hair. Head lice survive by biting the scalp and sucking blood though it. At any time, an infested person will have less than a dozen live lice on their head, although there may be hundreds of unhatched or empty egg sacs in the hair close to the scalp. These empty egg sacs are white and shiny and are known as “nits.”

Although unwanted, head lice cause minor problems and do not carry disease. They are an irritation and treatment is needed to remove them. Treatment is usually referred to as “delousing.” Treatment should not be started until the presence of at least one live, moving louse has been confirmed because the misuse of some toxic substances may cause more harm than the head lice themselves.

What causes a head lice infestation?
Head lice are unable to fly or jump and prefer to live on the scalp. Head lice are spread by direct head-to-head contact with a person who is infested. Head lice can affect people of any age but are more common in children because of the increased likelihood of direct contact. They die within a day of being removed from their human host and so are not found on furniture or household objects. There is no need to wash or fumigate clothing that has come into contact with head lice. Pets (eg, dogs and cats) do not carry head lice and do not need to be treated.

What are the symptoms of a head lice infestation?
Head lice infestation can cause the scalp to itch in some people but not in others. Itching is caused by sensitivity to lice saliva. The only other real “symptom” is finding a live louse in the hair. It is advisable to check children's hair regularly, particularly if an outbreak of head lice has been reported at their school or if they have been in contact with someone with head lice.

How should I check for head lice?
A technique known as “wet combing” is considered to be an effective method of detecting head lice. To do this, first wash the hair with an ordinary shampoo and apply conditioner before detangling the hair with a wide tooth comb. Once the hair has been detangled change to a fine-toothed “nit comb” (available in pharmacies) and comb through the hair methodically, starting at the roots and going down to the hair tips with each stroke. Check the comb for lice after each stroke. Once you have finished rinse out the conditioner and repeat the procedure. Wet combing can be carried out on a regular basis to check for lice before they can spread to other family members.

How are head lice treated?
As mentioned above, treatment should not be started until at least one live, moving louse has been found. An itchy scalp alone does not warrant treatment as dandruff or other skin conditions may be causing the problem. Once the presence of lice has been confirmed treatment can be started.

Washing the hair may dislodge a few active lice but the eggs will remain unharmed and able to hatch. Treatment with a lotion, mousse, solution or shampoo containing a chemical that will kill the lice is required. Available head lice treatments include ivermectin (Sklice), malathion (Ovide), permethrin (Nix)  and benzyl alcohol (Ulesfia). These preparations are known as pediculicides.

They are applied to the hair and left for some time before rinsing off (see specific instructions on the packaging). Lotions and solutions are generally considered to be more effective than shampoos because they remain in contact with the hair for a longer time. One treatment is usually sufficient to kill lice, but follow up in one or two weeks is advisable to kill any lice that may have hatched after treatment.

Cautions for use

  • The use of a head lice treatment may exacerbate existing skin problems.
  • Alcohol-based solutions are not recommended for use on younger children or on children with asthma.
  • Hair should be left to dry naturally rather than using a hairdryer or sitting by a fire.
  • Occasionally, lice may be found in facial hair or on eyelashes. These should be carefully removed; head lice lotions should never be used anywhere near the eye.

Resistance to head lice preparations is increasingly common, and in some areas a policy of rotation of different treatments is suggested to help prevent this. Your local doctor or pharmacist will be able to tell you which treatment is currently being used in your area.

An alternative, nonchemical option for treating head lice is the “combing” method. This involves combing through the hair and systematically removing any lice found. The success of this method depends largely on the concentration and skill of the person removing the lice. The use of aromatherapy oils such as tea tree or coconut oil for the prevention and treatment of head lice has increased over recent years. However, there is no reliable scientific evidence to support its use.

Further information
National Institutes of Health: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001843/

Last Reviewed: May 2013