Health & beauty
Headlice
Introduction
Headlice, nits, cooties - call them what you will - parents tear their hair out trying to treat them. So, how do you deal with headlice, and why do some treatments fail?
Mention headlice to any primary school parent and they're likely to regale you with stories of tedious hairwashing sessions and products that don't work. Unfortunately there's no magic bullet, but there are certainly some tricks worth trying to rid yourself or your children of the little critters.
We explain how to spot headlice, increase your chance of treating them successfully, and prevent reinfestation. Note: this report is a guide only and does not contain test results or product-specific recommendations.
How to spot headlice
What are headlice?
Lice are small, flat insects about 2mm to 3mm long that breed all year round. They live on the hair and come down to the scalp to feed and lay eggs. They feed on blood by sticking their tube-like mouthparts into your scalp several times a day.
Lice can't jump, fly or swim. They crawl very quickly from hair to hair and hold on with their claws. Lice can travel from one head to another when the two come very close together. Those found off the head are usually sick, old or injured and do not lay eggs.
Lice can live underwater - they stay on the head and don't die if you swim or shower.
Female lice lay about seven to 10 eggs each day. Eggs are laid close to the scalp with each egg firmly glued to a hair. Eggs hatch in around seven days (the empty egg case is technically the "nit" but many people call all eggs "nits"). A louse will live for up to 40 days.
Signs of headlice
Frequent itching is a sign of lice, but it's surprisingly unreliable. According to some studies, only about 30 percent of infected children get itchy. And almost as many kids scratch their heads when they don't have lice. If there are lice at your children's school or pre-school, check their heads regularly.
Eggs are not difficult to see: use a strong light and look at the hair. Newly laid eggs can be found within about 1.5cm of the scalp, while older eggs that have hatched sit further away from the scalp. The egg - or nit - is glued to each hair and take about seven to 10 days to hatch. Eggs will feel sandy or gritty when fingers are run through the hair. While there may seem to be a lot of eggs, only about a dozen lice at the most will be active at the time.
Live lice move quickly and are difficult to see, but small red dots behind the ears and on the nape of the neck may be headlice bites. Lice are usually between 2 to 4mm long and about 1mm wide. They have six legs with claws and are usually light or dark brown in colour depending on the child's hair colour (which they mimic).
Do's and Don'ts
What to do
If headlice have infested your family here's what you should try:
Use a conditioner and nit comb
The easiest way to find lice is to put lots of conditioner - at least three times as much as usual - on dry hair. Conditioner stuns the insects for about 20 minutes and makes them easier to comb out. Nit combs come in plastic or metal and range in price from $4 to over $20. Some have much finer teeth than others. You may need to experiment to find one that works well in your children's hair.
With the conditioner in, comb all over the scalp, especially around the hairline at the back of the neck, behind the ears and on the crown. Work through the hair one section at a time, from the roots out. Wipe the teeth of the comb on a clean tissue to see what lice and nits are being removed. Keep going until you can't find any more live lice. Sadly, even if you're very thorough, nit-combing may not work on its own.
Buy an insecticide-based treatment
The next step is a treatment based on an insecticide: either permethrin (or its variants phenothrin or d-phenothrin) or malathion (also called maldison). These treatments come as shampoos, lotions and sprays. There is no reliable evidence we know of that one product is more effective than any other. However, they are all likely to be more effective than just nit-combing.
Use the treatment exactly as stated
Follow the warnings and instructions carefully. Insecticides should kill the lice pretty quickly, but they won't kill live eggs, which will hatch over the next seven or so days. Most products suggest at least one repeat treatment up to a week or 10 days later, to get rid of any newly hatched lice. If the infestation is severe, you may even need a third application.
If there seems to be no significant reduction in the live lice numbers, and you're sure you've followed the instructions properly, don't use the treatment again. Try one with a different active ingredient.
Comb with conditioner
After you've used the treatment, repeat the combing/conditioner process as explained above. A combination of correctly applied insecticide and very thorough nit combing is your best bet for getting rid of headlice.
Treat everyone together
Treat every infected person in the house at the same time - and if your kids play with others who are infected, get them treated as well.
Try an electronic comb
A Robi electronic comb "zaps" lice with an electric current as it strikes them, injuring or killing some and making it easier to comb them out. Robi combs are expensive - you could suggest your school or pre-school group buys one to share.
Hot wash/hot dry
Lice will die quite quickly when not on a human head. But if you're worried about brushes and combs, hats and pillowcases, heat will also kill them. Wash the items in water at least 60°C, or spin them in the dryer set to hot. Do not apply hot water to a child's head: it will scald!
What not to do
- Do not treat unless the child is infected. These are not preventive products. They should only be used if you know there are insects to kill.
- You shouldn't need to cut or shave off the hair. Lice in short hair are easier to control, but it can be done with long hair.
- Do not use shampoo, conditioner or hair dryer on hair within 24 hours of using a chemical treatment. Each of these can make the treatment less effective or cause it to fail.
- Do not use ordinary insecticides, pet shampoo or flammable petroleum products.
- Do not use chemical products if the person applying the treatment or the person being treated is pregnant.
- Keep headlice treatments out of reach of children.
How treatments work
Insecticide products work by over stimulating the louse's nervous system, causing paralysis and death.
Resistance to insecticide products has been reported - although this is more likely to occur when a child has been repeatedly treated with these products over a considerable period of time. It appears that some lice survive that have a natural resistance to the chemical being used - and these survivors continue to breed and so create a personalised lice population that is resistant to a particular chemical. This may mean switching to another insecticide product or using other techniques.
Natural products claim to "remove", "combat" and "control" headlice rather than kill them. They work by stunning the lice, and it's important the hair is dowsed in product for at least an hour and combed immediately.
How effective are the treatments?
Insecticide treatments are likely to be the most effective and there is considerable research evidence to back this up. We asked the makers of natural products to provide us with evidence to support their claims. Much of the literature cited the same studies and some were performed on insects other than headlice or body lice (these insects were a similar size to lice). Other material provided was unpublished, so it was difficult for our researchers to comment on the methods used.
A study published in the New Scientist concluded that the use of alternative therapies, such as electric nit combs and essential oils, have yet to be proven in clinical trials.
There's been much debate about the effectiveness of "bug-busting" - which combines wet combing with hair conditioner. A recent article in the British Medical Journal suggests that bug-busting with this combination was four times more effective than two courses of insecticide treatment. But this contradicted a previous study in Wales in which malathion treatment was twice as effective as a bug-busting regime.
One of the possible explanations put forward for the higher cure rate of bug-busting was improvements to the fine-tooth comb. But a new study which looked at using a permethrin creme rinse (with and without combing) found permethrin without combing was marginally more effective.
But no treatment - neither chemical nor "natural" - is guaranteed to be completely effective. That's because none of them has been shown to kill all lice eggs. So a follow-up treatment is recommended seven to 10 days after the first application to break the egg/lice cycle.
From the far side
We found studies that tested the bizarre. One study tested six "home remedies" - vinegar, isopropyl alcohol, olive oil, mayonnaise, butter, and petroleum jelly (all which claim to work by smothering the lice). The aim was to see how effective they were in eradicating lice and eggs. The study concluded that petroleum jelly worked the best - but none of the home remedies killed all lice and eggs within 24 hours. The same study also found that lice are almost impossible to drown: they emerged, unharmed, after eight hours underwater.
What parents say
We've been inundated with responses from parents about how to deal with headlice - and many complain about the small fortune they spent on remedies from the chemist, only to find they didn't work. Combing proved to be the most effective technique: it works best if administered with a fine-toothed metal nit-comb. Many parents recommended a two-pronged attack involving regular combing and either ordinary hair conditioner (which stuns lice for 20 minutes) or a nit treatment from the chemist.
Some parents couldn't speak highly enough of the Robi Comb - a battery powered comb that can be used on dry hair and "beeps" when lice or eggs get caught in the teeth. Others found it a waste of time - particularly as it doesn't kill eggs.
Some parents advised dousing the hair in mousse and hairspray, which made it difficult for the lice to stick to the child's hair. Several suggested putting tea tree oil in the family shampoo, as a preventive measure - although there is little evidence to suggest that such treatment works.
Many parents were frustrated at their school's inability to deal with the problem, and some suggested schools should once again start running daily nit checks. But studies we found have shown a "no nit" policy at schools is not effective at eradicating headlice. Less than 20 percent of school children with nits will go on to develop infestations in 14 days; and about half of the children who are sent home with headlice don't have them. We think schools should take steps to advise parents if an outbreak of headlice is found at a school.
Why treatments can fail
According to Associate Professor Rick Speare of Australia's James Cook University, there are four main causes why headlice treatments fail.
1. Inadequate application of the product
This is usually a result of failing to cover the length of the hair or not applying enough product. One solution is to comb the product through the hair with a normal comb, making sure it covers the hair from root to tip. Also make sure hairs are lying parallel as you comb - this makes a nit comb easier to use.
2. Lice are resistant to the insecticide
Headlice can become resistant to one or more products - and there's no way of knowing in advance which products they are resistant to. But you can test for resistant lice. First, apply the product and leave it on for at least 20 minutes. Then, using a fine-tooth comb, comb from roots to tip and wipe the comb on a paper tissue. Look for movement. If the lice are active and walking around, they are probably strain-resistant. If they're dead or still, they are sensitive to the insecticide.
3. Failure to re-treat
No product kills all the eggs, which take about seven days to hatch. So you have to re-treat one week after the first treatment. If things are going well at this stage, you should expect to find nymphs (young lice) but no adults. Nymphs are smaller than adult headlice. To ensure that the lice have been completely eradicated, make sure you use the same product again. You should also recheck the hair at 14 days by wet combing. But only re-treat at this point if you find young lice. None of the products are preventive - they will only work on actual lice (young and old).
4. Reinfection
This is hard to detect. Check the hair weekly, by using the conditioner technique or a good metal comb. If the hair is clean one week, and lice are present the next, reinfection is highly likely. But don't blame reinfection until you have checked the first three failures. If you suspect reinfection, ask your child who they have had head-to-head contact with and see if these other children can be checked. (Being in the same room as an infected person does not transmit headlice.)
Myths and misconceptions
Herbal and essential oil treatments
There is no good evidence that tea tree oil or other such substances kill lice.
Other oils
Like conditioner, oils (including essential oils) make the lice easier to dislodge. Some people use olive oil, hair gel and even mayonnaise.
But although lice have died after being immersed in olive oil for some hours, the researchers who discovered this said there was no proof it would work on the human head. Lots of oil can be very difficult to remove.
Repellents
You can buy products that will supposedly keep lice away, but there's no evidence they work and they could even build up resistance. Don't use them.
Nit-checks at school
Some schools organise parents to come in and do nit-checks. Harvard lice expert Dr Richard Pollack says there is no evidence this reduces infestations. Parents often misdiagnose lice, and the process uses up precious school time.
Regular brushing
Despite frequent advice, brushing or combing may not reduce the risk. One study actually showed the opposite!