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  • What do head lice eat?
    Head lice are blood-feeding insects. They spend their entire life on the human scalp and feed exclusively on our blood.
  • How many lice can a person have?
    Far more than a thousand! The average number found is much lower though: 10-12 lice per lice-infected head.
  • Do head lice cause itching?
    Yes, but not always. When lice suck blood, they inject saliva to prevent the blood from clotting during the blood-sucking. This saliva may cause itching for some but not for everybody, thus itching cannot be used as a diagnostic symptom for head lice infestation.
  • Why do you require a specialized fine-tooth comb to search for head lice?
    Studies have shown that combing is four times more effective to detect head lice than using the fingers to part the hair and look for them. You need a prober and well documented fine-tooth comb in order to catch the lice and their eggs.
  • Does poor hygiene attract lice?
    No, lice feed on blood and not dirt. Just as many lice are found in clean hair as in dirty.
  • Can I get head lice from my pets?
    No, dogs, cats, horses, and birds - in fact lots of animals have their own kind of lice, but they cannot survive on humans. Conversely human lice cannot survive on animals.
  • I have detected head lice; how much cleaning and washing is needed in my house?
    It is always nice to have a clean home. However – it has no influence on the head lice. They live in the hair on the head and stay there. A lice that falls off the head is either dead or dying.
  • Can I drown the lice, if I go for a swim?"
    No. Even when lice are under water, their spiracles are not penetrated by the water. In fact, lice can endure several hours in water without being affected.
  • Is the playroom in the schools and day cares a greater source for infestation?
    It is often speculated that children get lice from playing in the playroom of schools because a lot of pillows and hairy teddy bears lay around. Children do not get head lice because there are head lice in the room itself. If children are infested in the schools, it is due to the fact when they play they often have more head to head contact – a perfect opportunity for the lice to crawl from one head to another.
  • Do we need to send the children home from school when we find lice on their heads?
    No; studies show that when lice are found on a child, they have typically been there for several weeks and as such is not an acute problem. However, it is important to inform the parents. The child must be under treatment before they are back to school.
  • Head lice are resistant towards head lice products, so do they work at all?"
    Some recent studies have found head lice resistance towards the traditional insect poison products in some countries. Today a broad range of products are available which act physically (and not through the nervous system). Head lice cannot develop resistance towards these products, which makes them very effective; and they kill insect poison resistant lice as well.
  • Can lice live in chest hair, eyebrows or beard?"
    Humans can be infested with three lice species: Head lice, body lice, and crab lice. Crab lice can be found in chest hair, eyebrows and beards but usually this kind of lice is found in pubic hair (in the crotch or armpits). However, in the western world crab lice are a species of lice in decline; probably due to the common shaving of pubic hair. Head lice cannot live in chest hair eyebrows or beards.
  • How Head Lice Infest
    Head lice are quick to infest hosts, but often perception of infestation risk is highly exaggerated. In fact, head lice only have very few ways of spreading to other hosts – being unable to either jump or fly – and as soon as they fail to have a firm grip on hair, they have difficulty in moving. No study has proven that head lice seek new hosts actively. Their chance of Survival in their Surroundings is very small, so infestation from one person to another happens more or less by chance.
  • Head To Head Contact
    Head lice only leave a head voluntarily if they get the chance to crawl over to another head. This is only possible when there is close contact between two heads. The hair of one person must be in close and probably prolonged contact with another person’s hair before a ‘transfer’ can take place. This contact must last long enough for the louse from one person’s head to grab a hair from the other person and move over on to the new host. Laboratory experiments with hair to hair transfer indicate that, even under the most ideal conditions, transfer of lice takes place in less than 10 per cent of the cases. Even though experiments indicate that lice transfers do not take place as frequently as we may think; head to head contact is considered the paramount means of infestation.
  • Infestation From Surroundings
    Head lice cannot survive for very long away from the scalp and then have hardly any chance of re-establishing themselves on another host, when they have been off a head. Thus, head lice that fall off the hair is either dead or dying. Nevertheless, disproportionately great focus has been placed on the risk of infestation from surroundings. Clothing such as caps, scarves and coats hanging closely together on a rack in a school or kindergarten have never been shown to constitute an infestation risk. On the contrary, several studies in schools show this possibility to be non-existent; therefore there is no need for special precautions in this area. Other studies show that, even though many pupils in a school or class host head lice, no head lice are found on the floor of the classrooms. Examinations of pillows from persons with head lice revealed only few cases of just one single small nymph. No studies have proven that hair brushes, combs, headphones or similar used by people infested with head lice play a part in the transfer of lice. Head lice cannot survive, neither, on our pets, teddy bears, dolls or other things with ‘fur’, so there is no reason to wash or clean them because of a head lice infestation.Even though infestation from surroundings cannot be excluded completely, specialists in lice all over the world agree that it does not make any sense to waste energy and time in controlling head lice on furniture, clothing, household items or elsewhere. It is important to bear in mind that most people, who share headwear, pillows, combs or brushes most probably are in close contact which pose a much bigger risk of infestation. The tenacious myth about infection of head lice from surroundings may originate from generations experiencing body lice. Body lice live in clothing and unlike head lice they can survive longer in the surroundings.
  • Who Gets Lice?
    Head lice are found in all countries, in all ages and in all strata of society. Unlike body lice, head lice are completely indifferent to the hygiene of the host, meaning that they thrive just as well in clean hair as in greasy hair.The type of people most likely to be exposed to lice infestation varies from country to country and depends highly on the social structure of the society with regards to housing, family models, school and childcare, as well as whether head lice infestation is socially accepted. In some countries it is unacceptable to have head lice, whereas in others it is regarded as a minor problem compared to other health issues the country is exposed to.Despite a sustained effort in many countries, the head lice problem still persists. One major factor is that many people are infested with head lice without knowing it. A study amongst students revealed that up to 60 per cent of those infested with head lice were unaware of it, and that every third infested student did not really care. Most parents reacted by treating their infested children, however more than 10 per cent of the parents ignored the problem. The percentage of the population infested with head lice varies a good deal from country to country and also depends on the groups studied. Most studies are done on school children and results show a variation from a few to nearly a hundred per cent in some groups. In other countries studies age did not show any significance when it comes to being infested with head lice. Girls (and women) are regarded as particularly infestation-prone. Again, studies show that this is not a general tendency in all countries. Other factors like housing, behaviour and hair length play a part as well. Other studies demonstrate, however, that hair length has less impact on whether people have head lice or not. Cramped housing may prone a higher risk than sex or hair length when it comes to exposure to head lice. In some countries – again, where school children have been studied – there is a clear tendency to find more cases of head lice after the school holidays. After the Christmas break, and especially after the summer holiday, cases of head lice flare up. This is probably due to the fact that the children have had contact to children outside the usual circle of friends during the holidays. Furthermore, parents tend to ‘forget’ all about head lice during the holiday periods. The flare up of head lice seen after the holidays draws renewed parental attention to the problem but after a while; when the amount of head lice has gone down again, parents start to relax and ‘forget’ to check their children. There are no decisive factors as to who gets head lice – everybody can get them. Close contact between people, undetected infestation and negligence of the problem are the main reasons to why head lice infestations remain a common problem.
  • The Life Cycle Of Head Lice
    Head lice (Pediculus capitis) are blood-feeding insects. They spend their entire life on the human scalp and feed exclusively on our blood. The egg is firmly attached to a hair close to the scalp, where the climate is sufficiently warm for the louse foetus inside the egg to develop. The development takes approximately seven days and then a new little louse is ready to crawl out of the egg. During the first three stages of the head louse lifecycle, in which it is not yet fully grown, the louse is called a nymph. Between each nymph stage the louse casts off skin and grows a little more. Each of the stages lasts about three days. Not until the louse casts skin after the third nymph stage to become an adult louse, is it possible to determine whether the louse is a male or a female. Shortly after this final skin cast the lice mate. Just 24 hours later the female lice are ready to lay eggs – and a new cycle begins
  • How Head Lice Live
    Head lice have adapted to solely live on the scalp of humans. This is where the lice find a temperature of about 30 degrees centigrade and a humidity of around 90 percent, and lots of food, which all in all gives them the optimal living conditions. By means of their very specialized mouthparts the head lice feed from the blood, which they suck from the skin on the scalp.The blood passes through the intestine of the louse and the nutrition and liquid are absorbed during this process. When the head louse needs food, it moves around very close to the skin and checks it out until it finds a suitable vein. The louse then pierces the skin with its mouth parts and adds saliva to the wound, to prevent the blood from clotting while the louse eats. The blood is ingested via two small pumps in the head of the louse. As the louse is partly transparent, you can actually see a thin thread of blood running from its mouth as it is pumped through the head and on into the intestine. Unlike body lice, head lice need food relatively often, thus they never leave their hosts. How often they need blood is not fully known. We do know, however, that head lice which feed only four times in 24 hours will die after a few days. Therefore, the lice probably have to eat at least six times in 24 hours in order to survive.
  • Symptoms
    Even though enormous effort is taken to exterminate head lice, they are still a recurrent problem. One reason is that it often takes too long before they are discovered. In these cases the host has probably posed an infestation threat to others for some time. Many people with head lice have no symptoms at all, even though itching may occur as a reaction to the saliva of the lice. The extent of itching depends on how long the lice have been present and how many they are. The first time a person gets head lice it will usually take some four to six weeks before itching starts, and during this period head lice may easily be passed on to others. In case of recurrent infestations, it usually takes no more than 24 to 48 hours until a host reacts to the saliva of the lice. Therefore, itching is a very poor indication as to whether someone is infested with head lice or not. Consequently, combing is the best way to make an early diagnosis and prevent an infestation. Thus, it is important that both children and adults at risk of being infested with head lice are regularly checked with a proper nit comb. The risk is always prevalent if others in the daily circle are infested, eg. in kindergartens and schools, amongst family and friends. If lice have been found within any group of people you associate, you should examine the members of your family regularly – at least once a week.
  • Diagnosis
    When examining a person for head lice, it is not sufficient to part the hair and check out the scalp visually. In most cases there will be only few lice present on the head, thus the probability of finding them by going through the hair with your hands is minor. Studies have shown that this method leads to a great number of head lice cases being overlooked. The most efficient method is to comb the hair with a proper fine-toothed comb. The distance between the teeth of the comb must not exceed 0.3 mm in order to catch the smallest nymphs. Combing can be done in both dry and wet hair. However, studies have shown that if you carry only a few lice (10 or less), the diagnosis is significantly more accurate when conditioner is applied to the hair before combing. This prevents the lice from moving around, thus making it easier to catch them with the comb – and it also makes it considerably easier to comb the hair.
  • How you check for head lice
    A combing takes approximately 10-20 minutes, depending on the thickness and length of the hair. The preparations are as follows: Place a towel around the shoulders Apply conditioner to the hair and comb the hair thoroughly with an ordinary hair brush Purchase a proper nit comb (see picture above) Have paper towel ready Daylight or good lighting – maybe also a magnifying glass You need to do as follows: Start combing in a parting in the middle in one side of the bangs right from the scalp Pull the comb meticulously along the scalp and all the way out to the tip of the tuft of hair Wipe the comb in the paper towel and check for lice Repeat the combing of the next tuft a little further from the bangs – wipe the comb Repeat all around the head and back again to make sure that all the hair has been combed thoroughly through Repeat the procedure systematically from one side to the other several times Combing must be carried out systematically from one side of the head to the other. After each pull, the comb must be wiped in a paper towel in order to check for lice. Combing with conditioner gives a 90 per cent certainty of finding lice cases, even if there is only a few lice – 10 or less. However, the method does not give 100 per cent certainty, so it is very important to repeat the process after a few days if an infestation is suspected. Should you find live head lice, you must start a proper treatment program with a lice product or by combing. To learn more about head lice visit .
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