 | Head lice are tiny wingless insects that live in human hair. They are common, particularly in children. Head lice are grey-brown in colour, the size of a pinhead when hatched and of a sesame seed when fully grown. They cannot fly, jump or swim and are spread by head-to-head contact, climbing from the hair of an infected person to the hair of someone else. A head lice infestation is not the result of dirty hair or poor hygiene. Head lice can affect all types of hair, irrespective of its condition and length. |
Life cycle of head lice
A female head louse lays eggs by cementing them to hairs (often close to the root), where they are kept warm by the scalp. The eggs are pinhead-size and difficult to see.
After 7-10 days, the baby lice hatch and the empty eggshells remain glued in place. These remains are known as nits. Nits glisten white and become more noticeable as the hair grows and carries them away from the scalp.
Head lice feed by biting the scalp and feeding on blood. They take 6-10 days to become fully grown. Once mature, a head louse can crawl from head to head.
A female head louse may start to lay eggs as early as seven days after she has hatched. To break the cycle and stop them spreading, they need to be removed within seven days of hatching.
How to spot head lice
In most cases, itching is the main symptom of head lice. It is not caused by the lice biting the scalp but by an allergy to the lice. However, not everyone experiences itching.
It's not always easy to see head lice, so detection combing is the best way of finding head lice. This involves using a special fine-toothed head lice comb (with tooth spacing of less than 0.3mm to trap the smallest lice) to comb through the hair. It works better on wet hair, but can be used on dry hair.
Detection combs are available from pharmacies.
Read more about detection combing.
Treating head lice
Usually, head lice can be treated effectively using medicated lotions or by wet combing, using a specially designed head lice comb.
Wet combing can be used without medicated lotions, but needs to be done regularly and can take a long time to do thoroughly.
Medicated lotion or spray can be used as an alternative. However, no medicated treatment is 100% effective. Your pharmacist will be able to recommend an over-the-counter lotion or spray.
Read more about treating head lice.
Preventing head lice
It's difficult to prevent a head lice infestation. Regular detection combing – such as on a weekly basis – is the best way to find new lice quickly.
Medicated lotions and sprays do not prevent head lice infestations and should only be used if a live louse has been found on yours or your child’s head.
How common are head lice?
Head lice are a common problem, particularly in school children aged 4-11 years.
It is not easy to tell exactly how common head lice are because the problem is often treated at home, with people only visiting their GP if treatment proves unsuccessful.
However, it is thought that more than 1 in 3 children in the UK will get head lice at some point during the year.
Head lice can be difficult to treat due to a high re-infestation rate and their ability to develop resistance to traditional insecticides contained in some medications.
It is thought head lice will not develop immunity to the newer silicone and oil-based preparations, because they have a physical rather than a chemical action on lice.
After a head lice infestation has been confirmed, you can treat the lice at home by wet combing the hair using a head lice comb, or by using medicated lotion (see below).
However, neither will protect against re-infestation if head-to-head contact is made with someone with head lice during the treatment period.
Wet combing
The wet combing method involves removing the head lice by systematically combing the hair using a special fine-toothed comb.
The comb's teeth should be spaced 0.2-0.3mm apart. Lice can be trapped between the teeth of nit combs with a tooth spacing of less than 0.19mm and remain unseen.
Combs are available from pharmacies, or you can order them online from the Community Hygiene Concern.
Medicated products do not need to be used for wet combing. This is good because head lice are becoming more resistant to the insecticides commonly used to remove them.
However, for wet combing to be effective, it needs to be regular and thorough. This is the method you should use:
- Wash the hair using ordinary shampoo and apply plenty of conditioner, before using a wide-toothed comb to straighten and untangle the hair.
- Once the comb moves freely through the hair without dragging, switch to the louse detection comb. Make sure the teeth of the comb slot into the hair at the roots, with the bevel-edge of the teeth lightly touching the scalp.
- Draw the comb down to the ends of the hair with every stroke, and check the comb for lice.
- Remove lice by wiping or rinsing the comb.
- Work methodically through the hair, section by section, so that the whole head is combed through.
- Rinse out conditioner and repeat the combing procedure.
- Repeat the procedure on days 5, 9 and 13, so that you clear young lice as they hatch, before they have time to reach maturity.
The length of time it will take to comb your child’s hair will depend on the type of hair your child has and how long it is. For example, short, straight hair can be quickly prepared and can be fine-toothed combed in a few minutes, whereas longer, curlier hair will take longer to comb.
Medicated lotion or spray
Using medicated lotion or spray is an alternative method of treating head lice. However, no medicated treatment is 100% effective. Your pharmacist will be able to recommend an over-the-counter lotion or spray.
Medicated treatments should only be used if a living (moving) head louse is found. Crème rinses and shampoos are not thought effective and are therefore not recommended.
Ensure you have enough lotion to treat everyone in your family who is affected. Use enough to coat the scalp and the length of the hair during each application.
Follow instructions that come with the medicated lotion or spray when applying it. Depending on the product you are using, the length of time it will need to be left on the head may vary, from 10 minutes to 8 hours.
The normal advice is to treat the hair and repeat the treatment after seven days. Some medicated products also supply a comb for removing dead lice and eggs.
Traditional insecticides must not be used more than once a week for three weeks in a row. Some products also carry a fire warning.
Some medicated products may be capable of killing eggs as well as lice, although there is no certainty of this. Check for baby lice hatching from eggs 3-5 five days after you use a product, and again 10-12 days afterwards.
At least two applications of lotion are needed to kill lice over the hatching period, because the lotions do not always kill louse eggs.
If the lice appear unaffected by the product (some lice may develop resistance to particular insecticides), or if the problem persists, seek advice from your school nurse, health visitor, pharmacist or GP.
Cautions
Always seek the advice of a healthcare professional before using medicated head lice lotions on the following groups:
It is recommended that pregnant women use either wet combing or 4% dimeticone lotion, which is licensed for use during pregnancy and breastfeeding.
You should always carefully read instructions before using medicated head lice lotions.
Afro hair
Afro hair or tightly curled hair can make treating a head lice infestation particularly difficult.
If your child has afro hair and they develop head lice, keeping their hair short will make treating it easier. Alternatively, you could try plaiting or braiding their hair, as this can make it difficult for head lice to attach themselves to the bottom of the hair strand.
Using a medicated lotion, such as dimeticone, and methodically combing small sections of hair at a time with a lice comb, will usually prove effective.
Head lice and clothing
Healthy head lice don't deliberately transfer on to clothing, bedding or soft toys, but can fall from the head onto these items. Their life span is about three weeks and when they fall from the head they're usually dying and unable to breed.
However, this is not always the case. If a healthy louse is dislodged onto clothing, linen or soft toys, it will always try to return to a host.
Hot washing or fumigation isn't necessary to control head lice. However, it is important to wash towels, bed linen and clothes that have been in contact with the affected person and check soft toys or give them a quarantine period.
Promptly dispose of any lice that fall from the head on to clothing or bedding.
Head lice on combs
Inspect brushes and combs that are used during treatment and remove any lice before the next stroke.
Head lice will die after a day or two if they're unable to feed on human blood.
Be aware that head lice can be flicked from dry hair during vigorous combing. If they land on someone they'll try to climb up to their head.