Head lice are tiny brown insects that can only live on human hair. They survive by sucking blood from the scalp. Head lice are easily spread by close contact, but do not spread disease.

Photo of a louse

Photo of a louse

They are very common, especially among school children and can affect anyone. Head lice are not a serious problem but they are difficult to remove.

What causes lice?

Head lice are tiny brown insects around three millimetres long – roughly the size of a sesame seed. They lay their eggs (nits) at the base of hair follicles. The eggs hatch after around seven days. They are fully mature adults, able to reproduce themselves, around two weeks later.

The life span of a female louse is around 40 days, during which time it can lay more than 100 eggs.

Lice only live on human scalps and they are not passed to or from animals. They can’t fly or jump but use their six legs to hold on tightly to scalp hairs.

Head lice can affect anyone and having them is nothing to do with hair type or style. Nor is having head lice a sign of dirty hair.

They are usually passed by hair-to-hair contact. The lice simply walk from one head to another. Outbreaks often occur in schools as children work and play closely together.

The lice die after a couple of days away from a human scalp.

What are the signs and symptoms of lice?

Head lice are usually visible in the hair and on the scalp, especially during brushing. Some children might also feel itchy. The eggs are white in colour and can be found near the scalp. Head lice can reproduce and mature very quickly, so a few can quickly grow in number over a very short period of time.

How are lice normally diagnosed?

A child has head lice if you can see them in their hair. There might also be tiny red spots on the scalp. A doctor can only confirm the diagnosis if they find a live louse.

How are lice normally treated?

If you suspect head lice, check the base of the hairs for eggs. They are oval, yellow or white, and tiny, less than one millimetre long. Also look carefully at the hair to see if you can spot adult lice. Favourite spots for infestation are behind the ears, and at the nape of the neck. If you can't see anything, try combing the hair with a fine toothed comb over a piece of white paper to see if any lice drop out.

Most people prefer to try natural methods to treat this problem first. This is a good idea because lice are becoming increasingly resistant to chemical treatments. The most effective is wet combing but it is hard work and you’ll need to be persistent.

The best procedure is as follows:

  • Wash the child’s hair and apply a generous amount of conditioner, which should be left in.
  • Use a good quality fine toothed steel comb and comb the child’s hair in small sections over a piece of paper so you can see the lice drop out. Wipe the comb clean on a piece of tissue between each stroke.
  • Continue until you can’t see any more lice or nits after combing. This will probably take at least half an hour.
  • Repeat every three or four days for at least two weeks so you remove any hatching lice before they have the chance to lay new eggs. You can’t remove the eggs by combing, only the lice.
Alternatively you could try an insecticide lotion. You will need to apply the lotion to all areas of the child’s scalp. It usually needs to be left in for up to 12 hours. For most brands, two applications a week apart are needed.

If lice are still present after the second application, they may be resistant to it. Try a different brand with different active ingredients.

It can take several treatments to get rid off the eggs and lice completely. Medicated shampoos and lotions contain quite strong chemicals, so some people may have an allergic reaction to them.

These lotions are not usually recommended for babies under the age of six months. Some brands are not suitable for children with asthma.

What’s going to help?

Cleaning combs and brushes regularly helps prevent transferring the lice back onto the scalp. Try not to share brushes with other people. Maybe have one for each child.

Check the rest of the family for signs of head lice and treat if necessary. Inform friends and family who may come into contact with a child with head lice. Also remember to alert the child’s school. Most schools have a head lice policy in place. They can advise whether the child needs to temporarily stay at home or can continue with school.

How can I reduce the risk of lice?

Check the child’s hair regularly for signs of head lice. Start treatment as soon as possible if the child has them. Do not use medicated lotions as a preventative measure. This only encourages resistant strains of head lice to emerge.

What happens next?

Head lice are not a serious condition and are not dangerous. But it is best to tackle it early to prevent it passing to others.

Last review date:
July 2011