Head Lice and Nits

Authored by Dr Mary Harding, 24 Aug 2016

Patient is a certified member of
The Information Standard

Reviewed by:
Dr Laurence Knott, 24 Aug 2016

Head lice are small insects which live in human hair and feed on blood from the scalp. Their eggs are called nits.

What are nits?

Dr Sarah Jarvis, GP and Clinical Director of patient.info

Just at the very thought of head lice, you are starting to itch, right? Head lice and nits are rife in school-age kids. Generously, kids may pass on the lice to their nearest and dearest, so they can be pretty common in parents too. Having head lice doesn't mean you are dirty or not washing enough. They are just common and easy to catch. And unfortunately, a right pain to get rid of.

How do these infections happen?

Head lice with match/comb

Image via Wikimedia Commons

Head lice are tiny little bugs which crawl around your hair (told you that you'd be itchy just reading ...), and nits are the eggs which they lay. The lice look like tiny little ants, and the eggs look like white spots clinging to hair strands. Nits look a lot like dandruff; in fact it's more or less impossible to tell the difference.

Lice feed from the blood on your scalp, and it is the bites (and your skin's reaction to the bites) which make you itch.

There's nothing too scientific about how you catch head lice. Just being close enough to someone else with head lice means the little beasties can walk from their head on to yours. The more hair available for lice transfer, the more likely this transfer is. So it's more common in kids with longer hair, and more likely if hair isn't tied up. Head lice don't jump and they don't fly, so you do have to have hair-to-hair contact. Fortunately, lice don't live for very long off a human head, but they do survive for a day or two, so you can also catch them by sharing a comb or hairbrush with someone with lice.

Find out more about the causes of head lice infection.

How can I tell if I have them?

Not all scalp itching is caused by head lice, and head lice don't always cause an itch. So the only way of telling for sure whether you have head lice is to see a live louse. If someone has quite a lot of lice, you may sometimes be able to see them just by looking through their hair. The best way to check for lice, however, is with a special nit detection comb. These combs have very fine teeth designed to pull out lice. If you have head lice, when you comb through hair, one or more tiny little beasties come out on the comb. You can buy the special comb from your chemist. 

Get more detail on how to detect head lice and on the symptoms of head lice.

How can I get rid of them?

You can get rid of head lice either by a combing method, or by the use of insecticides which you can buy from a chemist. Everyone in the house who has got confirmed head lice should be treated at the same time. Most insecticides need to be used twice, and combing has to be done several times over at least two weeks.

Read more detail on treating head lice.

How can I avoid getting them?

There is no magical anti-lice option that is guaranteed to stop you getting head lice. The main tricks are:

  • Check school children regularly for head lice.
  • Girls should tie their hair up at school so it comes into contact with other hair less.
  • If one person in the house has head lice, everyone else should be checked. Those who have head lice should then be treated.

Read more about preventing head lice.

Further reading and references

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