Head lice shampoos are the main weapon of parents and school teachers in their battle against head lice. There has recently been a lot of buzz in the media around the resistance of head lice to chemical treatments.
Some experts will tell you that this is a myth, and others state that resistant head lice are an established fact. Let’s try to shed some light on this controversial subject.
Are there more lice now than before? And is it because they are resistant to head lice shampoos?
We hear that there are more head lice now than a few decades ago. And we commonly read in the media that this is because head lice have become resistant to treatments and shampoos. Actually this is only a part of the truth.
What happens is that there were already a lot of head lice decades ago, but the treatments we used to get rid of them were much stronger – and harmful for our health – than today’s head lice treatment products. Many of us parents can easily remember our mothers pouring those lice shampoos on our heads and our scalp irritated during weeks or months after the treatment.
For safety reasons, many of these products have been banned over the years, and an actual head lice treatment shampoo is simply not as effective. So most of the time the lack of effectiveness of head lice shampoos is not related only to the resistance of head lice.
What about the resistance of head lice to head lice shampoos?
You may have heard of the increasing number of resistant head lice to commercial products such as Nix lice treatment or RID head lice treatment, and you may be wondering if this is true.
“Resistant head lice” means that the parasites will survive to treatments because they are genetically capable of doing so. First, it is important to realize that the resistance of head lice is a very controversial subject among scientists, pharmacists, healthcare professionals and manufacturers of head lice shampoos.
Some will tell you that from a scientific point of view, we cannot really say that head lice as a whole are resistant to chemical products because studies are scarce, local and sporadic and cannot really prove the resistance of lice.
And you will also hear that the insecticides that were very effective at the beginning of their use a few decades ago are becoming less and less active because head lice have adapted and genetic mutations have allowed the development of a phenomenon of resistance that makes the new generations of lice almost insensitive to the products.
A very recent study published in Proceedings of the National Academy of Sciences on June 21, 2010, has shown that lice have a genome that make them great candidates for resistance to insecticides. And many other scientific studies show resistant head lice in many regions.
And the truth is that head lice are actually resistant to insecticides in many regions of the globe, but not everywhere, and not for everybody. This is why head lice shampoos will still work very well for many people, and will not work at all for many other people.
