Many people use head lice products believing they will work and deliver on their consumer promise. They have been reassured that because of their mode of action (coating the surface of the lice and eggs and smothering them) the physical insecticides found in today’s most popular OTC products, have been considered to be resistance-proof. However, now there is evidence to suggest that this may not, in fact, be the case.
New Clinical Evidence On Head Lice Products’ Efficacy Is Emerging
In September 2023 Pharmacy Magazine reported on a recently published paper by Ian Burgess, the UK’s leading entomologist titled ‘Head lice: evidence that resistance to physically acting treatments is developing’ British Journal of Dermatology, 2023. The study concludes: “At this stage non-responsive lice have only been found in a few households but, as with resistance to insecticides found in the early 1990s, this is likely (to be) only the tip of a more extensive problem within the wider community”.
“If head lice are being selected for greater tolerance of immersion in physically acting fluids, product manufacturers, clinicians and regulators need to act now to establish not only which types of formulations and ‘active’ materials are losing their effect but also to develop alternatives to replace them before problems, similar to those encountered with insecticide use in the 1990s, become more widespread.”
Research Has Uncovered Head Lice Products Are Failing
After product use, following the proper product instructions they found evidence that the product had not worked:
“What we found was each of these individuals showed the full spectrum of louse development stages almost every week, which means the treatment did not kill the adults or perhaps the older nymphs that could then become adults.”
“Each of the people did not have infested family members and, in our follow-ups, we could not trace any contacts who had lice either. The failed treatments ranged across three completely different products, in one case a product that had not previously been used in the UK as far as we were aware at the time.”
Why Are Head Lice Products Failing?
According to Ian Burgess’s report “some of those failures were because the product did not work as expected. Lower efficacy has increasingly occurred over the years since the products were introduced, but there is no way of knowing whether these were chance issues or something more substantial affecting efficacy.”
Burgess continues: “In each case it is likely to either be some selected change in the proportion of different lipids in the waterproofing lipid coating of the louse, so they are not so easily disrupted.
“Alternatively, some of the products that enter the respiratory system of the louse to block it and stop the insects excreting water may be less easily able to do this if some difference in the structure of the spiracle has been selected for, so the fluid does not go in.”
If Lice Are Evolving Around The Product What To Recommend?
The NHS is reluctant to recommend any one specific product, and neither is NICE. Burgess agrees there is no simple answer.
One of the main issues is the lack of conclusive clinical evidence supporting treatments, as Burgess points out: “The problem is that very few products have actually been subjected to properly constructed clinical investigations.”
“As a result, we are all reduced to the level of trying something, seeing if it works and, if not, trying something else – not an attractive option given the cost and the angst head lice cause.”
Familiar Evidence From Hairforce Clients
Many of the Hairforce clients come to us because they have used the products and have found that with them, they have not cleared the infestation. Some still find head lice crawling and eggs that hatch. This trend is increasing.
The Hairforce clearing process does not use any head lice products, instead a combination of clever technology and forensic hand clearing, so head lice have no chance of developing any form of resistance to the process.
If you are using head lice products to tackle a head lice infestation, bear in mind that there is growing resistance to them. If you are clearing it yourself, then using a long-toothed metal nit comb to comb everything out of the hair will be more effective.
If you want to understand what The Hairforce does go to www.hairforceclinics.com or call us on 020 7485 7351,