What's making you itch?
By Hayley Birch
I had been scratching for three full days before I really started to notice the itching. But once I’d noticed it, it only seemed to get worse. Before I knew it, I was scratching so hard my own skin was beginning to pile up under my fingernails.Originally it had just been the bites. Bitey things love me; be they ants, mosquitoes or any kind of itchy scratchy-making midge, my flesh is a bitey things’ banquet. But I had a sneaking suspicion that now it was more than just the bites.
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I didn’t know what was making me itch more - the little munchers or the wax. And all this itching was making me even itchier. What had started out as a slight tingling had grown to an itch of epic proportions; I was caught up in a vicious itchy scratchy circle.
I set out to learn more about itching.
First stop, the US National Library of Health, where I was advised that “most itching is not serious”. However, I could be allergic, have scabies or be pregnant. Pregnant? Now that was something that hadn’t even crossed my mind.
Unbeknownst to me, during pregnancy, some women itch so violently that they scratch till they bleed. This is thought to be something to do with hormonal changes, including increased oestrogen. It’s also a consequence of a woman’s skin stretching to accommodate the growing child.
I was pretty sure I wasn’t pregnant, but the skin stretching thing started to play on my mind. Did my legs look fatter?
The next bit of itching trivia I came across was its clinical name: pruritis. Described as an itch or sensation that makes a person want to scratch, the cause of pruritis was for a long time considered a bit of a mystery. It involves histamine, the same chemical that is released during an allergic reaction, but until recently nobody quite knew how it connected with nerve signals to cause the itching.
Considering the vast number of conditions that cause a patient to suffer from itching, I found it surprising it had taken so long to work out the underlying mechanism. Eczema, xerosis (dry skin), poison ivy and all manner of nasty sounding rashes were cited as causes. Even my plain old insect bites got a mention, although I didn’t find anything about leg wax.
It finally emerged that we have ‘itch-selective’ neurons that aren’t stimulated by heat or touch. They are, however, very excited by chemicals. The original study describes how histamine, or mustard oil of all things, can be used to activate them.
I also came across some suggestions for treatment. These depended first on diagnosis, but among the expansive list was hydrotherapy (water therapy). Now this interested me because during my itchy rage, at a point where I was ready to tear off my skin with my teeth, a friend had volunteered a solution. Before I knew quite what was going on I’d had a huge wet lick administered to my arm. This was followed up by blowing on the offending bite. I was assured this would stop the itching.
It did, but only until the spit dried. Then I was back to scratching like a dog at a flea circus. So presumably, unless you’re going to immerse yourself in the bath throughout the mossie season, this isn’t any kind of a cure.
On the other hand, if your scratching is wax related, water may well serve some purpose. Only a full day later did I discover that having a shower and a good scrub pretty much clears up any remaining mint and relieves the itch. Serves me right for being dirty.
If this has started you itching to know more about the science of scratching, check out this paper at Nature. But please don’t stay there too long.
Other things that might bring you out in a rash:
Germy things
Spray on condoms
Maths puzzles
Locusts
Image: Hazel Moore
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