Head lice Dr Trisha Macnair Head lice and nits are common among children of school age. We look at how to spot them and the most effective treatments.

In this article

What are head lice? Symptoms

Causes and risk factors Treatment and recovery

Head lice are tiny insects that live on the head and in the hair. They're highly infectious and easily passed between children who tend to work closely with their heads together, at school and at play. Infestation of any of the hairy parts of the body is also called pediculosis. However, the type of lice found on the head are different to those that can infest the rest of the body or the pubic area.

Head lice are flat, wingless insects about 2mm to 4mm long, usually black or dark brown, which attach to the base of a hair. They are blood-sucking insects which feed on human blood several times a day. They stay close to the skin for moisture, food and warmth. The adult lice lay a large number of eggs, known as nits, that can be seen as tiny white/brown ovals glued firmly to the hair close to the scalp.

A head lice infection doesn't often cause symptoms. When it does the main symptom is itchiness - beware a child constantly scratching his or her scalp. Sometimes you see tiny red spots on the scalp or the lice and nits in the hair. (Nits are the eggs or empty eggshells after the lice have hatched.) Behind the ears is a favourite spot.

Head lice are widespread in the UK and almost all schoolchildren have at least one attack, if not more. Headlice affect those with long or short, dirty or clean hair – they are not a sign of poor hygiene or dirty hair.

Head lice can be caught by direct contact or by sharing combs, brushes and hats. Whole families are often affected.

Look for lice or nits by using a fine-tooth comb after washing the hair. Always check the whole family.

There are several ways to treat head lice. After washing the hair, apply lots of conditioner and comb it thoroughly with a fine-toothed comb - the lice and nits will be caught on the comb. (Rinse the comb in a basin of water to see them easily) You will have to repeat this for several days to catch all the lice and nits, and comb your child's hair daily to check for lice afterwards.

Alternatively, an electrically charged comb (available from pharmacies) can be used to catch and kill the lice. It must be used regularly.

Pesticide shampoo can be used, although some people are concerned about harmful side-effects and head lice in the UK are becoming resistant to chemical treatments. If you wish to use a pesticide shampoo, talk to your chemist about the most suitable one and follow the instructions as you may need to repeat the treatment.

Recently, a treatment called dimethicone has become available, which physically covers and smothers the lice.

To get rid of head lice, it's important to understand their life cycle so that you continue treatment for the right length of time. You may need to repeat treatments after 7-10 days – the time taken for the eggs to hatch- as the eggs are more resistant to treatments. If you are meticulous with treatment, there is a high chance of getting rid of the infestation.

Remember to check the whole family for nits, and to alert the parents of friends and your child's school.

This article was last medically reviewed by Dr Trisha Macnair in February 2009.