UK Edition
'Indestructible' head lice now resistant to over-the-counter remedies, researchers warn
Head lice have become immune to the most common treatments, new research has revealed, meaning parents are fighting a losing battle with nits in their children's hair.
Mutated "super lice" that cannot be killed by the most popular over-the-counter remedies threaten to create a headache for families across Britain this summer.
The itch-inducing pests already lead to missed school days and frustrated parents, who could have even more reason to be wary of the "indestructible" lice this year.
A US study has revealed that 98 per cent of head lice have developed a resistance to pyrethrins and permethrins - the active ingredients in most remedies available in pharmacies.
Authors of the report, based at Peyton Manning Children's Hospital in Indianapolis, urged parents of affected children to ask their doctor for alternative treatments to tackle nits.
Pyrethroids are a family of insecticides used widely indoors and outdoors to control mosquitoes and other insects.
It includes permethrin, the active ingredient in some of the most common lice treatments sold over the counter.
"This newly published data supports what we've been seeing in our offices and clinics: an increase in treatment-resistant super lice," said the study's lead author Dr Chris Belcher.
"It's important that parents contact a clinician if they suspect their child has head lice.
"There are effective, non-pyrethrin, non-pyrethroid-based prescription agents that can be used if treatment with over-the-counter products such as Nix has been unsuccessful."
Researchers collected pests between July 2013 and May 2015 from 48 US states.
They said the scale of gene mutation in lice was partly due to an estimated two-thirds of people overusing over-the-counter medications to tackle head lice.
Most treatments must only been used twice, but many patients surveyed by the experts said they had products at least five times before going to see a doctor.
Other parents had been mistakenly using the products on children who had dandruff in their hair instead of head lice, added Dr Belcher.
Head lice are small, wingless parasitic insects that live on human heads, drawing blood from the scalp and clinging to hair.
Although they do not spread infection, the can crawl and jump between heads and are notoriously difficult to eradicate.
Lice lay eggs on human scalps and hatch within a few days. They can be hard to spot as they are the colour of many hair types and the first sign that they are present is often when affected children scratch their heads.