Experts say people are wasting their cash forking out on products designed to kill the so-called "super lice" that no longer work.
The pesky bugs are a common problem, particularly preying on the scalps of school kids, aged four to 11.
But they have managed to evolve to become resistant to some of the treatments sold at chemists, scientists say.
Ian Burgess, of Insect Research & Development Limited, said when Lyclear Creme Rinse hit the market it "swept the board".
But, he warned, it leaves insecticide in a sufferer's hair.
While that may sound an appealing prevention measure, he said the bugs have slowly learned biologically to cope with it.
Global problem
Mr Burgess said that bugs coming into contact with the insecticide and surviving the encounter is a "worldwide phenomenon".
Research by Journal of Medical Entomology (JME) revealed that 98 per cent of head lice are now resistant to common treatments.
The 2016 study of 48 US states found that head lice were able to grow gene mutations, which helped them resist insecticides, also known as pyrethrins, pyrethroids, and permathrins.
Professor Craig Williams, of the University of South Australia, has been researching ways to outwit nuts.
Speaking to 7NEWS, he said: "Super lice would be the name we would give to lice that have become resistant to some of the treatments to kill them."
He likened the spread of the super-strength lice to antibiotic resistance - the more we use insecticides, the bigger the problem becomes.
His solution? Stick to the old trusty method.
"Cheap hair conditioner and a nit comb, and manually comb them out," Prof Williams said.
HEAD LICE FACTS
Head lice are tiny insects that live in hair.
Typically, they grow up to 3mm long, making them are difficult to spot.
They can cause an itchy scalp and general discomfort as the parasites live by feeding on human blood.
Nits are particularly common in school children aged between 4-11.
But here's some facts you might not have heard about nits...
They can’t fly, jump or swim
They are very unlikely to be spread by items such as combs, hats or pillows
They don’t have a preference for dirty or clean hair – nor short or long
They are specific to people – you can’t catch them from animals
Once they have been removed from hair, head lice will usually die within 12-24 hours
Superbugs
Dr Sarah Jarvis, GP and clinical director of Patient.info, told The Sun Online warned of problems in recent years with topical head lice treatments.
She said: “Head lice are tiny brown-grey insects, about the size of a sesame seed, which thrive on the scalp.
"Nits are the white eggs they hatch from. These stick to the hair – usually close to the scalp – and are often still seen after treatment has killed all the lice.
"There are two main treatments for head lice. The first is strictly physical – wet combing using conditioner and a specially designed ‘bug busting’ comb.
"It’s time consuming and needs to be repeated several times - repeated every few days until you’ve had three sessions in a row where you have not seen any live lice.
"However, it is very effective when done properly and can be used regularly to check for new infestations.
"The second is to use topical treatments - lotions etc - to kill the bugs. These are divided into two main types.
"The first are chemical insecticides, which poison the lice. There have been lots of problems in recent years with head lice becoming resistant to these chemical insecticides.
"The second type is the physical insecticide. These work by smothering the lice and we have seen far less resistance to these treatments.
"Your pharmacist can advise on the treatments recommended in your area.”
