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By Bjarne Lühr Hansen PhD, MD and Philipp Skafte-Holm MD, Mentor Institute

Head lice can become a plague in many schools and kindergartens. It is very difficult to find the lice while the nits are easier to find. The nits look like dandruff but stick so hard to the hair that you cannot pull them off like you can with dandruff. Only children who have lice should be treated. There are many different remedies against lice but the head lice are getting more and more resistant. A fine-toothed comb is an effective alternative.

A plague of lice in a school or kindergarten occurs especially after a longer holiday like the summer or winter holiday. This means that most children are bothered by lice from August to October and in January.

Especially children between 3 and 11 years old are exposed to being infected with head lice. With smaller children lice are equally common with boys and girls. When the children grow older the lice are more common with girls. Many believe that lice are seen in connection with dirty hair – this is incorrect. Frequent hair wash will not prevent lice either.

The louse is a bug that feeds off human blood from the scalp. The head louse is 2 to 4 millimetres long and greyish. The head louse lives down right by the scalp where the temperature and moisture sustains it. It moves quickly through the hair and can therefore be difficult to spot.

It is easier to find nits – they look like dandruff or fine powder. The nits stick so hard to the hair that they are difficult to remove. You can easily distinguish nits from dandruff by pulling a hair between your thumb and index finger. The nits stick to the hair while the dandruff slides off. You check for lice by dividing the hair into partings every 2 centimetres and checking the entire scalp this way. Lice and nits are frequently found in the back of the head and behind the ears.

When you have had lice for some time the scalp begins itching. Bites from the lice itch and sometimes cause red spots near the bite. If the child scratches the bites, small rips may arise that bacteria can access and thereby infect the scalp. Such an infection can be identified by redness, warmth, swelling and soreness in the scalp.

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All can be infected with lice, no matter how clean you are, and long, dirty hair is no more liable to lice than short, clean hair is. Lice live of blood, not dirt.

Head lice spread by lice crawling from head to head. Lice cannot fly or jump so it only spreads if two heads are in contact over a longer period of time.

Head lice combed out of the hair are old and sick and are unlikely to infect anyone. Un-hatched nits in furniture, combs, hats and scarfs can be responsible for spreading head lice. Therefore you must expect to be infected when borrowing a comb, brush or hat from a child with head lice.

What can the school and kindergarten do if it is hard to put an end to the plague of lice?

A good idea can be to name a certain date ‘lice day’. All children, parents, siblings and staff are informed about how to check for lice and how the certain remedy is used correctly. On ‘lice day’ everyone are checked for lice and the same evening all with lice or nits are treated with the remedy. ‘Lice day’ is repeated after one week.

Day care:

The child can attend day care when the treatment has commenced.


Only children with lice need treatment. It is important to check the entire family for lice on a daily basis – as long as there are lice in the community – and that everyone infected with lice or nits are treated. If there are more than one member of the family infected with lice they must be treated simultaneously, otherwise they will keep infecting each other over and over.

There are different kinds of remedies against lice that can be bought over the counter. Most people choose to use a shampoo because it is easiest to use. Head lice become more and more resistant towards the remedies. Therefore it is important always to repeat the treatment after one week. It is a good idea to check the effect of the treatment after 24 hours when the lice are supposed to be dead. If there are lice still alive after a correct treatment, the treatment should not be repeated with the same remedy, but instead another remedy is chosen. Remember that if you do not use the remedy correctly, it does not have the desired effect. Read the instructions that follow the remedy to be sure you use it correctly.

Can lice become resistant towards remedies against lice?

Yes. Recent studies show that head lice become more and more resistant. It is therefore recommended to use both a remedy against lice and a fine-toothed comb.

What can you do?

Fine-toothed combing is an old and known method for delousing. The method is cheap, non-toxic and can be very effective. If you use a traditional fine-toothed comb, it is a good idea to wet the hair, apply a conditioner and comb it before you start the fine-toothed combing. The hair is then easier to comb with the fine-toothed comb and the lice are calmer. All the hair must be combed from scalp to hair tip.

It is very important to start every stroke with the fine-toothed comb by the scalp since this is where most lice are found. After every stroke the fine-toothed comb must be cleaned or tapped clean onto a white underlay where you can see how many lice are combed out of the hair. All grown lice must be removed with the first combing of the hair so that no more nits are laid. Since the very small lice can be hard to catch with the fine-toothed comb and nits previously laid will hatch in the following days it is important to repeat the combing on a daily basis for two weeks. After this you should be free of lice, if the combing has been done correctly and you have not been infected again.

Contact the doctor tomorrow

If the child has head lice in spite of correct treatment with a remedy against lice. If redness, warmth, swelling and soreness occurs in the scalp.

Contact the doctor immediately

This is never necessary.