As any parent of a school-age child will know, head lice are a near-constant source of irritation – spreading rapidly through classrooms and seemingly returning just when you thought you’d finally got rid of them.
The tiny, blood-sucking insects live in the hair and on the scalp, where they feed, breed and lay eggs that cling stubbornly to strands – while their bites can trigger maddening, relentless itching.
And September can be a particularly troublesome time, as millions of children pile back into classrooms after the summer holidays, and once again come into close contact with their classmates.
One online pharmacy reported that, last year, sales of head lice treatments jumped by 57 per cent in September.
But getting rid of the playground pests isn’t always as straightforward as parents might hope.
Experts warn that head lice have developed resistance to some of the insecticides once routinely used to kill them, including permethrin and malathion – meaning treatments that worked reliably in the past may now fail.
And gone are the days of the nit nurse checking pupils’ scalps for the bugs, leaving spotting and treating infestations largely to parents at home.
So, with countless products lining pharmacy shelves and dozens of supposed home remedies promoted online, we asked some of the country’s leading experts what actually works – and how to banish stubborn head lice for good.
Head lice are tiny blood-sucking insects that infest the hair and scalp, where they feed and lay eggs close to the skin
How do children catch head lice?
Head lice expert Dr Ian Burgess, director of the Medical Entomology Centre, explains: ‘Lice have been around for as long as human beings have been around.’
But contrary to popular belief, they cannot jump or fly. Instead, they crawl from one person’s hair to another – which is why prolonged head-to-head contact is by far the most common way they spread.
It is thought a louse can transfer from one scalp to another in as little as 30 seconds.
‘Children pick them up from friends and siblings when playing, whether that be in the playground at school, in the park, at clubs, in the garden or at family social events,’ says Dr Burgess.
‘If you’ve ever watched children playing, particularly girls, there is lots of close physical contact, including head-to-head touching, which is how they spread.’
And while infestations often become apparent when children return to school in September, Dr Burgess says they may actually have picked them up during the summer holidays.
That’s because it can take several weeks for an infestation to become obvious – particularly as itching may not begin immediately.
It is possible for lice to spread via shared hats, brushes, pillows or towels, but experts say this is far less common because the insects are adapted to living on the human scalp and don’t survive for long once separated from it.
And what about the age-old claim that head lice are a sign of dirty hair? It’s a myth. Studies show the insects have no preference for clean or dirty hair and can infest either equally.
How to spot head lice
The only sure sign that you or your child has head lice is finding a live, moving louse in the hair.
Adult head lice are tiny – roughly the size of a sesame seed – and greyish-white to brown in colour. Their eggs are even smaller and are firmly glued to individual hairs, usually close to the scalp, particularly behind the ears and around the nape of the neck.
Unlike dandruff, which can usually be brushed or shaken from the hair, lice eggs are difficult to dislodge because they are stuck firmly to the hair shaft.
A head lice infestation can be identified through the presence of live and moving lice
The easiest way to check is with a special fine-toothed detection comb, which can be used on wet or dry hair. Work systematically from the roots to the ends, checking the comb for lice after each stroke.
Itching is often the first thing parents notice, along with a tickling or crawling sensation in the hair. Repeated scratching can also leave small red bumps or sore patches, particularly around the back of the neck and behind the ears.
But an itchy scalp alone doesn’t mean your child has head lice – and some people with an infestation experience little or no itching.
Dr Leila Asfour, of the British Association of Dermatologists, stresses that treatment should only begin once a live louse has been found. Head lice products should not be used as a preventative measure.
Over-the-counter treatments
When it comes to getting rid of head lice, Dr Burgess says most parents understandably reach for a bottle of treatment – but what is inside it matters.
Broadly, treatments fall into two camps: traditional insecticides, which poison the lice, and newer ‘physical’ treatments, often containing silicone-like substances, which kill the insects without relying on conventional pesticides.
And experts say there is good reason to choose carefully.
For decades, head lice were routinely treated with insecticides such as permethrin and malathion. But repeated exposure has allowed the insects to evolve resistance, meaning some lice can now survive doses that would once have killed them.
British studies have found widespread resistance to both permethrin and malathion – prompting the popular description ‘super lice’.
Indeed, the NHS now specifically advises against head lice products containing permethrin because they are unlikely to work.
This is one reason physical treatments have largely taken their place.
One pesticide-free option is Hedrin 4% Lotion (£15.30 for 150ml, boots.com), which contains dimeticone – a silicone-based substance that coats the lice and physically interferes with their ability to survive.
It is applied to dry hair, left on for eight hours or overnight and then washed out.
But killing the live lice does not necessarily mean the infestation is over. Some eggs can survive treatment and hatch several days later, starting the cycle again.
‘Even if a product says it can be used with one treatment, you should always repeat it after a week and check to make sure there are no lice emerging over the next week to ten days,’ says Dr Burgess.
Wet-combing is ‘most effective’ method
It may be laborious, but many experts say wet combing remains one of the most effective ways to get rid of head lice – not least because the insects cannot develop resistance to being physically removed.
The method involves washing the hair normally, applying plenty of conditioner and then working through the entire head in sections with a fine-toothed detection comb, pulling it from the roots right through to the ends.
After each stroke, the comb should be wiped on a tissue or rinsed so you can check for live lice.
The best way to catch head lice is periodically checking your child’s hair with a nit comb
And research suggests it can outperform some chemical treatments. A study by the London School of Hygiene & Tropical Medicine found that a systematic wet-combing method cleared head lice in 57 per cent of cases, compared with just 13 per cent among children given certain insecticide treatments.
The crucial point is that combing once isn’t enough. Eggs left behind can hatch later, so the process needs to be repeated to catch young lice before they mature and begin laying eggs of their own.
The NHS recommends wet combing on days one, five, nine and 13, followed by another check on day 17 to make sure the infestation has cleared.
Dr Burgess recommends using a comb with flat-faced teeth no more than 0.3mm apart – narrow enough to catch tiny newly hatched lice as well as adults, which could slip through the wider teeth of an ordinary comb.
And everyone else in the household should be checked too. Anyone found to have live lice should be treated at the same time, otherwise the insects can simply pass back and forth between family members.
No need to wash soft toys
The good news is that if your child does catch head lice, there’s no need to start frantically stripping beds, scrubbing the sofa or putting beloved teddy bears in the freezer.
That’s because head lice are exquisitely adapted to living on us. They need regular blood meals and the warm, humid conditions close to the scalp to survive – and quickly struggle once separated from their human host.
‘You don’t need to do any special cleaning, you don’t need to boil your sheets and nothing needs to go into a freezer,’ says Dr Burgess.
‘Any louse that was stupid enough to climb off on to the bed while you’re asleep will dehydrate within eight to 12 hours.’
And because lice spread overwhelmingly through direct head-to-head contact rather than via bedding, clothes or furniture, a major household deep-clean is unlikely to make much difference.
Instead, experts say your time is better spent checking everyone in the household and treating anyone who has live lice.
Can head lice be prevented?
Pharmacy shelves are flooded with preventive ‘defence sprays’, specialised shampoos and essential oils such as tea tree, rosemary and peppermint, all promising to make children’s hair less inviting to lice.
But there is little good-quality clinical evidence that any of them reliably prevents an infestation.
‘Short of having no friends, it’s not possible to prevent your child getting lice,’ says Dr Burgess. ‘It’s a natural part of social development.’
Nor should children with head lice be banished from the classroom. The NHS says there is no need to keep them off school once an infestation is discovered.
For children with long hair, keeping it tied back may reduce the opportunities for hair-to-hair contact, although it is no guarantee against picking up lice.
More useful is getting into the habit of checking your child’s hair regularly with a detection comb – particularly if you know lice are circulating among their friends or classmates – so an infestation can be caught and treated before it has a chance to become well established.
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