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7th January, 20215 min read

Head lice vs dandruff: how do I tell the difference?

Medical reviewer: Dr Ann Nainan
Author: Helen Prentice
Last reviewed: 22/12/2020
Medically reviewed

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

If you’ve got an itchy head, or white bits in your hair, you’re probably wondering what it is. You might have heard of dandruff – flakes of skin that appear in hair – and head lice – insects that live in hair – but how do you work out if you’ve got one or the other?

Read on to learn what head lice and dandruff are, so you’ll be able to tell the difference. You’ll also find tips for treating and avoiding both conditions, and when it’s worth seeing a doctor.

What do head lice look like?

Head lice are tiny insects that live in the hair on your head. They vary in colour from grey-white to black, and they’re about 3mm long (the size of a sesame seed).

Their small size makes them quite hard to see, but you’re most likely to spot them on the hair behind your ears or the back of your neck. They don’t hurt, but they can make your scalp very itchy, so it’s a good idea to treat them as soon as possible. This will also stop you from giving them to anyone else.

Head lice are very common in children under the age of 12, especially children with longer hair. But they can’t jump or fly, so you can only get them from touching heads with someone who has them. And, despite what you might have heard, there’s no evidence that they prefer either dirty or clean hair.

Female head lice lay eggs, which can attach to your hair. The eggs hatch in about a week, leaving behind a little egg case called a ‘nit’. Because nits are white, they’re often easier to see in your hair than the lice. From a distance, they might also be confused with dandruff.

What does dandruff look like?

Dandruff is a very common condition that affects the skin on your head (scalp). It causes little bits of skin to flake off, and these flakes then appear in your hair. They’re usually more noticeable if you have dark hair, but they can also fall out of your hair, so you may see them on your clothes.

If you have dandruff, your scalp may feel itchy and dry. But it’s good to know that it’s not harmful, and you can’t catch it from other people.

Dandruff can be more obvious when you don’t wash your hair, but it’s not caused by not washing it enough. Cold weather and stress may make it worse, however.

Treating and preventing head lice

There’s not much you can do to avoid head lice, especially if you have young children. But it’s a good idea to check for them regularly – particularly if you hear that people at your child’s school have had them.

Combing hair with a fine-toothed comb can help you search for head lice – ask a pharmacist about a suitable comb. If you do find them, it’s best to get rid of them as soon as possible.

You can try to remove head lice by wet combing the hair with a fine-toothed comb. Follow these steps:

  • wash the hair with shampoo
  • apply lots of conditioner
  • comb through the hair, from the roots to the tips
  • check the comb for lice after each stroke, and remove any you see
  • repeat the steps above 4, 8 and 12 days later, to catch any new lice
  • check everyone’s hair again on day 17

You can also use medicated lotions or sprays to kill head lice. The instructions will tell you how long to leave them on the hair – some need to be left on overnight and can cause irritation so are not suitable for everyone. Once the lice are dead, you’ll need to comb them out of the hair.

The treatment might need to be repeated after a week to catch any new lice that have hatched. There’s no need to keep children away from school while you’re treating them.

Treating and preventing dandruff

Dandruff is best treated with an anti-dandruff shampoo, which you can find in pharmacies and supermarkets.

Check that the shampoo you buy contains one of these ingredients:

  • salicylic acid
  • zinc pyrithione
  • ketoconazole
  • coal tar
  • selenium sulphide (or ‘sulfide’)

It can take a month or so for anti-dandruff shampoo to start working, and you may have to try a few types before you find the one that works for you. If you’re unsure, ask your pharmacist for advice.

When to see a doctor

With head lice, you can usually treat them at home without needing to visit a doctor.

If an anti-dandruff shampoo hasn’t improved your dandruff after a month, it’s worth seeing your doctor. You should also get medical advice if your dandruff is bad, or your scalp is very itchy, red or swollen. This is because there are other skin conditions that can cause these issues.

Key points

  • head lice are very small insects that live in hair, and can be difficult to see
  • dandruff is small flakes of skin from your head – you may see them in your hair or on your clothes
  • wet combing is recommended to help find and remove head lice
  • medicated lotions and sprays are also available to treat head lice
  • dandruff can usually be treated with an anti-dandruff shampoo
  • if your scalp is very itchy, red or swollen, speak to your doctor
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