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.

PROMOTED VIDEO
Life and Style
ebookNow available in paperback
Life and Style
ebooksA superb mix of recipes serving up the freshest of local produce in a delicious range of styles
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

    Recruitment Genius: Ruby On Rails Developer

    £45000 - £50000 per annum: Recruitment Genius: This is a fantastic opportunity...

    Recruitment Genius: PHP Web Developer

    £25000 - £35000 per annum: Recruitment Genius: This an exciting opportunity to...

    Recruitment Genius: Lift Engineer

    £28000 - £35000 per annum: Recruitment Genius: Lift Engineer is required to jo...

    Recruitment Genius: 2nd Line IT Support Engineer

    £24000 - £30000 per annum: Recruitment Genius: This company (Microsoft World W...

    Day In a Page

    In a world of Saudi bullying, right-wing Israeli ministers and the twilight of Obama, Iran is looking like a possible policeman of the Gulf

    Iran is shifting from pariah to possible future policeman of the Gulf

    Robert Fisk on our crisis with Iran
    The young are the new poor: A third of young people pushed into poverty

    The young are the new poor

    Sharp increase in the number of under-25s living in poverty
    Greens on the march: ‘We could be on the edge of something very big’

    Greens on the march

    ‘We could be on the edge of something very big’
    Revealed: the case against Bill Cosby - through the stories of his accusers

    Revealed: the case against Bill Cosby

    Through the stories of his accusers
    Why are words like 'mongol' and 'mongoloid' still bandied about as insults?

    The Meaning of Mongol

    Why are the words 'mongol' and 'mongoloid' still bandied about as insults?
    Mau Mau uprising: Kenyans still waiting for justice join class action over Britain's role in the emergency

    Kenyans still waiting for justice over Mau Mau uprising

    Thousands join class action over Britain's role in the emergency
    Isis in Iraq: The trauma of the last six months has overwhelmed the remaining Christians in the country

    The last Christians in Iraq

    After 2,000 years, a community will try anything – including pretending to convert to Islam – to avoid losing everything, says Patrick Cockburn
    Black Friday: Helpful discounts for Christmas shoppers, or cynical marketing by desperate retailers?

    Helpful discounts for Christmas shoppers, or cynical marketing by desperate retailers?

    Britain braced for Black Friday
    Bill Cosby's persona goes from America's dad to date-rape drugs

    From America's dad to date-rape drugs

    Stories of Bill Cosby's alleged sexual assaults may have circulated widely in Hollywood, but they came as a shock to fans, says Rupert Cornwell
    Clare Balding: 'Women's sport is kicking off at last'

    Clare Balding: 'Women's sport is kicking off at last'

    As fans flock to see England women's Wembley debut against Germany, the TV presenter on an exciting 'sea change'
    Oh come, all ye multi-faithful: The Christmas jumper is in fashion, but should you wear your religion on your sleeve?

    Oh come, all ye multi-faithful

    The Christmas jumper is in fashion, but should you wear your religion on your sleeve?
    Dr Charles Heatley: The GP off to do battle in the war against Ebola

    The GP off to do battle in the war against Ebola

    Dr Charles Heatley on joining the NHS volunteers' team bound for Sierra Leone
    Flogging vlogging: First video bloggers conquered YouTube. Now they want us to buy their books

    Flogging vlogging

    First video bloggers conquered YouTube. Now they want us to buy their books
    Saturday Night Live vs The Daily Show: US channels wage comedy star wars

    Saturday Night Live vs The Daily Show

    US channels wage comedy star wars
    When is a wine made in Piedmont not a Piemonte wine? When EU rules make Italian vineyards invisible

    When is a wine made in Piedmont not a Piemonte wine?

    When EU rules make Italian vineyards invisible