Department of Health

Head lice identification and treatment

Key messages

  • Head lice are small, wingless, blood sucking insects.
  • People get head lice from direct hair-to-hair contact with another person who has head lice.
  • Treatment involves a lotion applied to the head of the person and washing of the person's pillowslip.
  • Insecticide resistance can occur, repeated treatment with different product can help with this.

Head lice

Anyone can get head lice, no matter how clean the child's hair is.

What they look like

  • Head lice are small, wingless, blood sucking insects.
  • Their colour varies from whitish-brown to reddish-brown.
  • Their lifecycle lasts anywhere form 32-35 days in which they lay eggs.

How they spread

  • People get head lice from direct hair-to-hair contact with another person who has head lice.
  • Head lice do not have wings and cannot jump, so they cannot fly or jump from head-to-head, they can only crawl.

Lifecycle of head lice

  1. Egg is laid on hair shaft. An egg is called a nit.
  2. Louse emerges after 6 to 7 days.
  3. First moult 2 days after hatching.
  4. Second moult 5 days after hatching.
  5. Third moult 10 days after hatching.
  6. Emerging from their third moult as adult lice, the female and slightly similar male begin to reproduce.
  7. Female lays first egg 1 or 2 days after mating.
  8. Female can lay approximately 3 to 8 eggs per day for the next 16 days.
  9. Having lived 32 to 35 days the louse dies.

Treating head lice

Hair treatment

  • Concentrate on the head. No treatment kills all of the eggs so treatment must involve 2 applications 7 days apart.
  • If you are using lotions, apply the product to brushed, dry hair.
  • Combs with long, rounded stainless steel teeth positioned very close together have been shown to be the most effective, however, any head lice comb can be use.
  • There is no need to treat the whole family, unless they also have head lice.

Washing bed linen and communal areas

  • Only the pillowcase requires specific laundering; either wash it in hot water (at least 60 degrees centigrade) or dry it using a clothes dryer on the hot or warm setting.
  • There is no evidence that you need to clean the house or classroom.

Preventing head lice

There is no product available that prevents ‘catching’ head lice. However, tying long hair back and checking weekly for lice, using the conditioner and comb method, can help prevent the spread.

Insecticide resistance

Insecticide resistance is common, so you need to check that the lice you comb out during a treatment are dead.

If the insecticide has worked, the lice will be dead within 20 minutes. Treat again in 7 days using the same product to ensure proper treatment.

What to do if the treatment hasn't worked

If the lice are not dead, the treatment has not worked and the lice may be resistant to the product and all products containing the same active compound.

Wash off the product and treat as soon as possible using either a product containing a different active compound or the conditioner and comb method.

The active compounds in head lice products are:
• pyrethrins
• synthetic pyrethroids (permethrin, bioallethrin)
• organophosphates (maldison or malathion)
• herbal, with or without natural (non-chemical) pyrethrins.

Safety when using head lice products

Any head lice product can cause a reaction and should be used with care by women who are pregnant or breastfeeding, children less than 12 months old and people with allergies, asthma or open wounds on the scalp. If you are unsure, please check with your pharmacist or doctor.

Reviewed 10 October 2023


Contact us

Do not email patient notifications.

Communicable Disease Section Department of Health GPO Box 4057, Melbourne, VIC 3000

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