Head Lice: What They Are and How to Get Rid of Them


Published: 03 March 2020

If you’ve ever had head lice, you’ll know that they aren’t easy to get rid of. So much so, in fact, they’ve managed to exist for thousands of years - head lice were even around long before human evolution (Better Health Channel 2018).

Head lice are small wingless biting insects. They live and breed in human hair and feed on blood from the scalp.

An adult louse can range from a whitish-brown to reddish-brown colour and is about two to four millimetres in length. Lice eggs, called ‘nits’, are oblong-shaped, white or brown in colour and attached to hair shafts (SA Health, 2019). The warmth from the human head acts as an incubator, causing the nits to hatch (Better Health Channel 2018).

Incubation Period

Once a female louse has laid her first eggs on a new host, they will hatch after seven to ten days. From here, the nits will progress through their short life cycle consisting of three stages: egg, nymph and adult. The total lifespan of a louse is only 32-35 days, but after mating, each female can lay three to ten eggs per day. These eggs will then hatch and continue the cycle (Health VIC n.d.).

lice lifecycle
Breaking the cycle of head lice.

Infectious Period

As long as there are living eggs or lice on a person’s head, that individual is infectious to others (SA Health 2019).

How Lice Spread

Lice are transferred between people through direct head-to-head contact. They can not fly or jump but will crawl from one person to another (Health VIC n.d.).

Lice spread through being in close proximity to others in times such as playing and cuddling, so children and families are most commonly affected (Better Health Channel 2018).

Without a human host, lice can not survive for more than two days (SA Health 2019).

There are different species of lice that live on animals such as dogs and cats, but they can not be spread to people, and vice-versa (SA Health 2019).

Head lice can sometimes be transferred by using or sharing items that someone with lice has recently used. These items may include:

  • Combs and brushes;
  • Hair accessories;
  • Hats and scarves;
  • Headphones;
  • Towels;
  • Upholstery; and
  • Pillowcases.

(SA Health 2019, Mayo Clinic 2018)

Symptoms of Head Lice

Head lice are commonly associated with itching on the scalp, neck and ears, which is caused by an allergic reaction to louse saliva. However, many people will not experience any itching, and it is possible to have a lice infestation without knowing (Mayo Clinic 2018).

Diagnosing Head Lice

The best way to detect lice is to use the ‘conditioner and combing’ or ‘mechanical’ method (Health VIC n.d.).

These are the steps:

  • Make sure hair is dry and detangled.
  • Cover all of the hair with conditioner and separate it into sections.
  • Thoroughly comb through each section of hair with a fine-toothed lice comb.
  • Wipe the comb onto a white tissue and check for lice or nits.
  • Comb each section of the head about four to five times.
  • If lice or nits are found, seek treatment.

(Better Health Channel 2018; Health NSW 2014)

This process should be repeated every second to third day until no more lice or nits can be found (Health NSW 2014).

lice comb
The best way to detect lice is to use the ‘conditioner and combing’ or ‘mechanical’ method.

Treatment Strategies For Head Lice

  • The conditioner and combing method: While this does not kill lice, it stuns them and allows them to be removed manually.
  • Chemical removal using a treatment that contains insecticides: Chemical treatments need to be repeated because most of them do not kill eggs. Some lice may be resistant to particular active compounds, so chemical treatments do not always work.
  • Washing pillowcases in hot water (at least 60 degrees celsius) or putting them in the clothes dryer on a hot or warm setting.

(Health NSW 2014; Health VIC n.d; Better Health Channel 2018.)

Head Lice Prevention

There is no product that can prevent head lice. However, there are some strategies that may help stop lice from spreading. These include:

  • Tying back long hair;
  • Encouraging children to avoid head-to-head contact with other children during play, sport and other activities;
  • Avoiding sharing hats, scarves and hair accessories with other people;
  • Avoiding sharing brushes, combs and towels with other people; and
  • Refraining from lying on beds, couches, pillows, carpets or stuffed toys that have been in contact with someone who has head lice.

(SA Health 2019; CDC 2019)

Once someone has successfully treated head lice, the following strategies may stop them from coming back:

  • Washing any bed linen, stuffed animals and clothing used two days prior to treatment in hot water (at least 60 degrees celsius) or putting them in the clothes dryer on the hot setting for at least 20 minutes;
  • Dry cleaning items that can not be washed or putting them in airtight bags for two weeks;
  • Vacuuming carpets and upholstered furniture;
  • Soaking hair brushes and accessories in hot water or throwing them away; and
  • Checking other family members for lice.

(KidsHealth 2019; SA Health 2019)

Although head lice can be tricky to deal with, they are not dangerous and do not spread disease (Healthdirect 2018).

lice washing
Wash any bed linen, stuffed animals and clothing used two days prior to treatment in hot water.

Additional Resources


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