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Head lice

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Head lice (Pediculus capitis) affect only humans, and cannot be passed on to, or caught from, animals. Infestation with head lice is also known as pediculosis.
Brought to you by NHS Choices



Head lice are tiny (pin-head sized) grey-brown, wingless insects that live by sucking blood from the scalp. Their eggs, which look like tiny white specks, are known as nits and are laid glued to the base of hairs.

The eggs hatch after seven to 10 days, and 10 to 14 days after hatching the lice are mature and 2-4mm long (the size of a sesame seed). Once mature they start to reproduce, so numbers can grow alarmingly if not treated.

Head lice are common in schoolchildren, particularly between the ages of four and 11, but anyone with hair can catch them.


Symptoms of head lice

Infestation often causes itching of the scalp, but may also go unnoticed. If you suspect head lice, check the base of hairs for eggs and comb the hair over a piece of white paper to see if you can spot any dark mature lice.

Sometimes an infestation is marked by tiny red spots on the scalp. Lice may be visible in the hair behind the ears and at the nape of the neck as these are favourite spots for infestations.


Causes of head lice

Head lice are transferred by close hair-to-hair contact. They cannot jump, fly or swim, but walk from one hair to another. It is a misconception that head lice infestation is as a result of dirty hair and poor hygiene. Head lice can be found in all hair types, long or short, and in hair of any condition.


Diagnosing head lice

The presence of head lice is indicated by repeated itching of the scalp, or by detecting them in your hair. This can be done using a special fine toothed comb available from your local pharmacy. Your GP, or practice nurse, can only confirm the diagnosis if a live louse is found in your hair.

If you, or your children, have head lice you should check the rest of the family and alert close friends, and your child's school.

Itching is not always present because it is not caused by the lice biting the scalp, but by an allergy to the lice themselves. Some people are not allergic to them so may not notice they have been infested, and it can take up to three months after the initial infestation for itching to develop.


Treating head lice

Head lice are difficult to remove because of their size, reinfestation rate, life cycle and their ability to develop immunity to insecticides. Lice can be a persistent and recurring nuisance, so it is important to treat them quickly and thoroughly.

Once infestation is confirmed it can be treated at home by either using a wet comb with conditioner, or medicated lotions, combined with a special nit comb available from pharmacies.

Wet combing method

Wet combing, or 'bug-busting' is used to remove lice without using chemical treatments. This method can be helpful because head lice are growing increasingly resistant to the insecticides used to remove them. The best procedure is as follows:

  • wash the hair as normal using an ordinary shampoo,
  • apply conditioner liberally to wet hair (this causes the lice to lose their grip on the hair),
  • comb the hair through with a normal comb first,
  • with a fine tooth nit comb, comb from the roots along the complete length of the hair and after each stroke check the comb for lice and wipe it clean. Work methodically over the whole head for at least 30 minutes,
  • rinse the hair as normal,
  • repeat every three days for at least two weeks.

Medicated lotion or rinse

Ask your pharmacist for an over-the-counter (OTC) insecticide lotion or crème rinse. Only use a lotion if you find a living (moving) head louse. Apply the preparation according to the instructions, and remove the lice and eggs with a fine-toothed nit comb. You should take care when applying treatment because the preparations are usually toxic. The normal advice is to treat once, and repeat seven days later.

Always ask for advice before using medicated lotions on young babies (under six months), pregnant women or people with asthma, or allergies, and always read the instructions carefully.

Sometimes complementary therapy treatments such as tea tree oil are recommended for treating head lice, but their effectiveness has not yet been proven.

There is no need to wash clothing, or bedding, if they have come into contact with head lice. This is because head lice quickly die without a host to provide warmth and food.


Preventing head lice

There is no prevention for head lice infestation other than normal hair care and checking yours and your family's hair and scalp periodically.

If your child has long hair, tie it back as this helps to reduce the likelihood of contact between their hair and that of an infected child.

Do not use medicated lotions or rinses 'just in case', for example in close friends or family members. They should only be used if live lice are found. Regular combing of hair using the bug-busting method (see treatment section) can help with early detection as well as treatment

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This article was originally published by NHS Choices

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