Comment: We've all had an itch we need to scratch, but what exactly is it?

As new research claims to hold the key to suppressing the irritating sensation, Steve Connor explains what causes an itch

Science Editor

An itch is not a tickle, although some people may think it is funny. Neither, according to the latest research, is an itch a form of pain, although try telling that to people tormented by chronic, long-term scratching.

The scientific evidence for one of life’s odder sensory experiences is that the sensation of itch depends on a dedicated set of nerve cells leading from the spinal cord to the brain, complete with their own chemical messenger, a neurotransmitter known as Nppb.

Take away Nppb and the itch disappears. Put it back again in the spinal cord, and the irritating sensation returns. It is easy to see a potential for a drug that blocks Nppb in chronic scratchers.

The worst type of itch that most of us will suffer from is the temporary sort that comes after a mosquito bite. This is a result of the immune system releasing a substance called histamine into the skin to counteract all the nasty ingredients found in a mosquito’s saliva.

Most itches – even the seven-year variety – eventually wane and disappear, especially with a bit of an effort to avoid scratching them too much. But there are some itches that just won’t go away – such as the one that led a distressed Massachusetts woman to scratch right through her skull case to expose the brain.

An itch is loosely and simply defined as an unpleasant sensation that provokes a desire to scratch. It is thought to have evolved as a defence against parasites trying to burrow through the skin, but the sensation seems to have a psychological as well as a physical component – an itch can be brought on merely at the thought of something itchy.

Certainly the fear of chronic itching inspired one of the tortures described in Dante’s Inferno: “the burning rage of fierce itching that nothing could relieve”.

One of the worst things about an itch, of course, is that once you develop the habit, it is difficult to stop. Scientists call this the “itch-scratch cycle”. So what may have started out as a pleasantly relieving hobby becomes an addictively painful occupation.

Life and Style
ebookNow available in paperback
ebooks
ebookPart of The Independent’s new eBook series The Great Composers
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    Ashdown Group: Part-time Payroll Officer - Yorkshire - Professional Services

    £25000 per annum: Ashdown Group: A successful professional services firm is lo...

    Recruitment Genius: Inside Sales Manager

    Negotiable: Recruitment Genius: Join a worldwide leader in data-driven marketi...

    Recruitment Genius: Business Adviser - Sales and Marketing

    £30000 - £35000 per annum: Recruitment Genius: Do you have a desire to help sm...

    Recruitment Genius: 1st Line Support - Helpdesk Analyst

    £18000 - £21000 per annum: Recruitment Genius: This company is a customer focu...

    Day In a Page

    Syrian conflict is the world's first 'climate change war', say scientists, but it won't be the last one

    Climate change key in Syrian conflict

    And it will trigger more war in future
    How I outwitted the Gestapo

    How I outwitted the Gestapo

    My life as a Jew in wartime Berlin
    The nation's favourite animal revealed

    The nation's favourite animal revealed

    Women like cuddly creatures whilst men like creepy-crawlies
    Is this the way to get young people to vote?

    Getting young people to vote

    From #VOTESELFISH to Bite the Ballot
    Poldark star Heida Reed: 'I don't think a single bodice gets ripped'

    Poldark star Heida Reed

    'I don't think a single bodice gets ripped'
    The difference between America and Israel? There isn’t one

    The difference between America and Israel? There isn’t one

    Netanyahu knows he can get away with anything in America, says Robert Fisk
    Families clubbing together to build their own affordable accommodation

    Do It Yourself approach to securing a new house

    Community land trusts marking a new trend for taking the initiative away from developers
    Head of WWF UK: We didn’t send Cameron to the Arctic to see green ideas freeze

    David Nussbaum: We didn’t send Cameron to the Arctic to see green ideas freeze

    The head of WWF UK remains sanguine despite the Government’s failure to live up to its pledges on the environment
    Author Kazuo Ishiguro on being inspired by shoot-outs and samurai

    Author Kazuo Ishiguro on being inspired by shoot-outs and samurai

    Set in a mythologised 5th-century Britain, ‘The Buried Giant’ is a strange beast
    With money, corruption and drugs, this monk fears Buddhism in Thailand is a ‘poisoned fruit’

    Money, corruption and drugs

    The monk who fears Buddhism in Thailand is a ‘poisoned fruit’
    America's first slavery museum established at Django Unchained plantation - 150 years after slavery outlawed

    150 years after it was outlawed...

    ... America's first slavery museum is established in Louisiana
    Kelly Clarkson: How I snubbed Simon Cowell and become a Grammy-winning superstar

    Kelly Clarkson: How I snubbed Simon Cowell and become a Grammy-winning superstar

    The first 'American Idol' winner on how she manages to remain her own woman – Jane Austen fascination and all
    Tony Oursler on exploring our uneasy relationship with technology with his new show

    You won't believe your eyes

    Tony Oursler's new show explores our uneasy relationship with technology. He's one of a growing number of artists with that preoccupation
    Ian Herbert: Peter Moores must go. He should never have been brought back to fail again

    Moores must go. He should never have been brought back to fail again

    The England coach leaves players to find solutions - which makes you wonder where he adds value, says Ian Herbert
    War with Isis: Fears that the looming battle for Mosul will unleash 'a million refugees'

    The battle for Mosul will unleash 'a million refugees'

    Aid agencies prepare for vast exodus following planned Iraqi offensive against the Isis-held city, reports Patrick Cockburn