They are the bane of many parents’ lives.
Not only do headlice cause incessant itching, but treating them is an ordeal in itself, with tears, tantrums and products often potent enough to knock you out.
And as the schools go back – and we hit peak nit season – hundreds of thousands of youngsters will be affected.
Why? Because the small insects are highly adapted to one type of environment: hair on a human’s head – especially primary school-aged children.
Infuriatingly, in the battle of human’s vs headlice, it’s the parasite that’s winning.
Scientists have warned that lice are becoming increasingly resistant to products – leaving parents with fewer options than ever.
The small insects are highly adapted to hair on school-aged children’s heads, experts warn
And last year, it was reported that a strain of ‘super lice’ was now affecting half of the states in the US.
These so-called ‘super lice’ are resistant to 98 per cent of over-the-counter remedies’ – containing pyrethrins and permethrins – the active ingredients in most popular treatments.
This is because they carry genetic mutations which make them immune to the pesticide.
In the UK, this resistance figure is 87 per cent, according to research published in the Journal of Medical Entomology.
Yet two-thirds of parents with school-age children have dealt with an infestation, a poll by Puressentiel, a company that makes clinically proven essential oil products, found.
On average, families face three or four encounters with the itch-inducing insects while their children are at school, one in 10 parents has been forced to deal with 10 or more infestations.
And while lice are becoming resistant to many popular treatments, a big part of the problem is parents not letting on their children have nits – enabling them to spread to other members of their child’s class, says Dr Gill Jenkins, a GP in Bristol.
‘Usually it’s because they are embarrassed, but there are some parents who unfortunately don’t – or can’t – deal with lice effectively, causing other kids to become infested,’ she explains.
Getting the the root of the problem
In recent years, the appetite for chemical treatments has plummeted – not only because they are because they are becoming less effective, but because parents are reluctant to smother their children’s scalps in such potent substances – sometimes for several hours at a time.
In fact, the NHS has advised against the use of pesticide-based chemical treatments for some time, explains Dr Chris Etheridge, a practicing medical herbalist and plant medicine expert.
Earlier this year, French academics warned chemicals in head lice treatments could lead to behavioural problems in young children.
Pregnant women exposed to pyrethroids – a group of synthetic chemicals used in common pesticides – were more likely to have children who develop social behaviour problems by the age of six, their study found.
The chemicals were developed by British scientists in 1960s as a safe alternative to organophosphates – the basis of many insecticides, herbicides, and nerve agents.
And as the schools go back – and we hit peak nit season – hundreds of thousands of youngsters will be affected, they say
But the researchers, from the University of Rennes, suggested pyrethroids may not be as safe as previously thought.
They suspect the chemicals might alter neurochemical signalling in the brain, altering a child’s development.
Now, there is a second generation of treatments which use a physical action to kill lice – and these are recommended by the NHS, explains Dr Etheridge.
‘Some coat lice in a greasy film of dimeticone, a type of silicone which works by coating the lice, stopping them from getting the supply of water they need to stay alive,’ he explains.
The problem, he says, is that dimeticone treatments must be left in the hair for eight hours.
And with their pungent smell and oily consistency, they are widely loathed by parents and children alike.
‘As a parent myself, I used to worry about putting such strong chemicals on my children’s heads – especially for periods of several hours,’ says Dr Jenkins.
‘Some of the chemicals are so strong that their fumes can cause breathing difficulties, especially in people suffering with conditions such as asthma.
‘Such products are also clearly not advisable for people with sensitive skin or eczema.’
Not only that, the preparations can be so greasy that they carry warnings about slipping and it can be difficult to rinse them out with normal shampoo.
Indeed, ‘anecdotal reports of washing-up liquid being required to remove it are common,’ a report published in the journal Prescriber warned.
A new way to fight nits
Research is increasingly showing that essential oils have potent pesticidal properties – and are a natural, chemical free weapon in the war on headlice.
‘Although they are often lumped together, there is a huge range of different herbal treatments on the market,’ explains Dr Etheridge.
‘Most use one or more essential oils, but their effectiveness — or lack of efficacy — is dependent on the combination, concentration and quality of the oils used.
‘There is compelling evidence that tea tree, lavender and eucalyptus all have some anti-lice activity, and plant oils which block the louse’s respiratory system, in much the same way as dimeticone, have also been shown to be effective.
‘But it is very much buyer beware. Just because a product contains some of these ingredients, it does not guarantee it will work.
‘And whatever product is used, it’s important to comb the hair thoroughly with a fine-toothed comb afterwards, to remove dead lice and dislodge any which might have avoided coming into contact with the treatment, or have had minimal exposure.’
A study published in the journal Parasitology Research reported a 100 per cent kill rate using a 1 per cent solution of tea tree oil.
And an Australian study published in BMC Dermatology found a combination of tea tree and lavender oils was as effective as a ‘suffocation’ product, with both delivering 97.6 per cent clearance, compared to just 33.3 per cent from a pyrethrin based treatment.
Researchers commented that the tea tree and lavender oil combination ‘exceeded the efficacy of another essential oil product’.
Meanwhile an evidence review, reported in BMJ Best Practice, found: ‘Herbal and essential oil treatment containing eucalyptol [the active agent in eucalyptus oil] may be more effective at eradicating lice compared with [a traditionally used chemical called] malathion.’