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4th January, 20214 min read

Where do head lice come from?

Where do head lice come from?
Medical reviewer: Dr Ann Nainan
Author: Caroline Bodian
Last reviewed: 30/12/2020
Medically reviewed

All of Healthily's articles undergo medical safety checks to verify that the information is medically safe. View more details in our editorial policy

Head lice are tiny insects, about the size of a sesame seed, that live in the hair on your head.

Anyone can get head lice, but they’re more common in children. You get them from close contact with someone who has them.

Read on to learn more about how head lice spread, how to tell if you have them, and what you can do to get rid of them.

Who gets head lice?

Head lice are common in children between 4 and 11 years old, and they’re most common among 7 and 8 year-olds. They’re also more likely to be found in long hair. Despite what some people say, however, they don’t prefer dirty hair – they’re just as likely to live in clean hair.

How do head lice survive and spread?

You may have heard that you can get head lice from sharing hats or pillows with other people. This is unlikely, however, as they can’t live very long once they’re not in someone’s hair – they need blood from the skin on your head (scalp) to survive.

Head lice pass from one person to another through close contact. They can’t jump or fly – it takes a louse about 30 seconds to crawl from one person to another.

Friends eating popcorn on bed at home

How do you know if you have head lice?

If you have head lice, you’ll usually have less than 20 lice on your head, though in rare cases there can be as many as 1,000.

As they’re dark and small, head lice can be hard to see. You may be more likely to spot the small white egg casings that they hatch from. These stick to your hair, and are known as nits. Having nits doesn’t always mean you have live head lice, but it’s best to check for lice if you find nits.

Even if you don’t spot lice or nits, you might feel them, as head lice can make your head itchy. (Conditions such as eczema and dandruff can also cause an itchy scalp.)
Headlice with nit comb in background

How do you treat head lice?

If you find head lice, you should treat them as soon as possible – and everyone you live with should be checked to see if they have them, too.

Wet combing is an effective way to remove head lice. It involves using a fine-toothed comb, following these steps:

  1. Wash your hair with regular shampoo.
  2. Apply lots of conditioner.
  3. Use a fine-toothed comb to go through your hair in sections, from the roots to the ends.
  4. Each time you pull the comb through your hair, check it for lice or nits and remove them.
  5. Repeat these steps every 4 days, for 4 times in total.
  6. After 17 days, check that your hair is free of lice.

If wet combing doesn’t work, you can ask a pharmacist or doctor about trying a medicated lotion or spray. These treatments will generally kill head lice within a day, although you may need to reapply them a week later to catch any newly hatched lice.
Mother using a comb to look for head

How do you prevent head lice?

There’s not much you can do to prevent head lice, other than checking for them regularly. In fact, if you have children under the age of 12, you may want to check them as much as once a week.

The best way to stop other people getting head lice is to find them as early as possible – then you can begin treatment and stop the spread.

Key points

  • head lice are tiny insects that live in the hair on your head
  • they are most common in children aged 4 to 11 years old
  • they spread through close contact with a person who has them
  • they can be treated at home by wet combing the hair, or applying medicated lotions

Head lice and nits
Dandruff

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Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.

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