Head lice

Also known as nits, kutis, kutu bugs, utu or riha.

Head lice are small insects that live on the human scalp. They are common and cause concern and frustration for parents, children and young people. In general, head lice are harmless as they do not carry or spread other diseases, but they are annoying and can be hard to get rid of.

Key points

  1. Head lice spread easily through close head-to-head contact with other people. 
  2. They are most common in children aged 3 to 11 years, who can pass them on to family and friends before anyone realises.
  3. Anyone can catch head lice; catching them has nothing to do with not being clean.
  4. If you find live head lice or eggs on a family member’s scalp, treat them and check the scalp of everyone in the house.
  5. Dimethicone lotion is a very effective treatment that your family doctor can prescribe.
  6. Wet combing with cheap conditioner and a head lice comb is also an effective way to find and remove head lice if done thoroughly.

What are head lice?

Head lice are small, wingless-shaped insects that live and lay eggs on your scalp. The scalp provides food and warmth for the eggs to hatch.

Head lice live on your hair and feed by sucking blood from your scalp. They are pale grey (before feeding) and reddish brown (after feeding). Head lice do not carry or pass on disease.

Adult lice can grow to about 2–3 mm, or about the size of a sesame seed. You can see them with the naked eye, but unless you've seen them before, it’s easy to confuse them with dandruff. They live for about 30 days and can lay 4 to 6 eggs per day (which last up to 2 weeks).

The eggs are much smaller and paler than the lice (about the size of a pinhead). They can be found stuck to individual hair shafts, near the scalp, where they have been laid by the adults.

After the egg has hatched, the empty shell is called a nit and can become easier to see as the hair grows out.

Who can get head lice?

Anyone can get head lice. They are a common problem and cause concern and frustration for parents and children.

Catching head lice has nothing to do with poor hygiene.

How do people get head lice?

People get head lice from head to head (hair to hair) contact with someone who already has head lice. This can easily happen when children play or sleep together and their heads touch.

Head lice can only crawl from hair to hair. They can't fly or jump from head to head.

Head lice only survive on humans. They die quickly when they are not on the head, usually within 24 hours.

How do I check for and get rid of head lice?

Head lice can live all over the head but particularly like warm places behind the ears, around the bottom of the hairline, and on top of the head. They can look like grains of sand or dandruff.

Two recommended head lice treatment methods are wet combing and dimethicone 4% lotion.

Whichever treatment you use, you need to thoroughly treat anyone with live lice or eggs at the same time.

Wet combing – to find and treat head lice

Wet combing with cheap conditioner and a fine-tooth head lice (nit) comb is an effective way to find and remove head lice, if done properly. You don't need to buy ­expensive products to get rid of head lice. You can buy a fine-tooth head lice comb from your pharmacy. It can take up to an hour to do a wet combing session. It depends how long and how thick your child's hair is.

If you find lice or eggs, wet comb every day if you can manage it, or at least every 2 to 3 days. You can stop when you find no lice or eggs for 3 days in a row. 

See KidsHealth's step-by-step guide to wet combing 

Dimethicone 4% lotion – to treat head lice

Dimethicone 4% lotion is a very effective head lice treatment your doctor can prescribe. It is fully subsidised on prescription (you do not have to pay).

Dimethicone kills head lice by suffocation (blocking their air supply) and stopping them from being able to regulate water. It is not an insecticide.

How to use dimethicone:

  • Apply the lotion to dry hair, using enough product to thoroughly moisten the hair and scalp, and combing it through with a regular comb.
  • Leave on for at least 8 hours (overnight) before washing off.
  • Repeat the treatment 7 to 10 days later.
  • Dead eggs can be removed with a fine-toothed nit comb.

Other treatments

You can buy head lice treatments that contain insecticides from your supermarket or pharmacy. Some of these products are becoming less effective because head lice have developed resistance to them. They are also more likely to cause itching and irritation than dimethicone.

Because dimethicone works by suffocation, it is highly unlikely that lice will develop resistance to it.

If you choose to use another chemical or natural treatment, speak to your pharmacist, doctor or nurse for advice about what treatment to use and how to use it. Read more about other treatments.

Never use fly spray, kerosene or treatments intended for animals – these may harm children and adults.

What about checking and treating other family members for head lice?

If you find head lice, you should check the rest of your family. If you find head lice on other family members, treat them all on the same day.

If your family has head lice, tell anyone who has had head-to-head contact with them, so that they can check and treat their family if needed.

Tell your school so that they can tell other parents to check their children for head lice and treat if necessary.

Can you prevent head lice?

It's very difficult to prevent getting head lice – there are no products available for this.

Tying long hair back and checking weekly for lice, using the conditioner and comb method, can help prevent the spread.

You don't need to wash clothing and bedding on a hot wash – it's unlikely to help prevent the spread of head lice. 

Learn more

Head lice KidsHealth, NZ
Head lice Ministry of Health, NZ

References

  1. Appropriate use of head lice treatments Medsafe Prescriber Update, March 2017  
  2. Treating head lice BPAC, June 2008
  3. A parent's guide to head lice American Academy of Pediatrics
  4. 4% dimethicone lotion: a subsidised treatment for head lice BPAC, May 2017
  5. Head lice New Zealand Formulary
  6. Head lice Ministry of Health, New Zealand 
Credits: KidsHealth NZ & Health Navigator Editorial Team. Last reviewed: 06 Mar 2019