The number of people who are wrongly convinced they are seriously ill is rising.

　　’I was living with this constant fear that I would be dead in three months，“ says Mark. The 32-year-old from Manchester had a pain in his lungs and immediately suspected advanced lung cancer. It became， he says， ”an obsession“。 His GP was certain it wasn’t cancer， but Mark couldn’t stop thinking about it. He returned to his doctor several times， eventually persuading him to arrange a scan at the hospital. This too showed he didn’t have the disease. Eventually Mark realised what he was suffering from was not lung cancer， but health anxiety.

　　Catherine O’Neill， services manager at the helpline charity Anxiety UK， says the disorder ”is one of the things we get most calls about. The common fears are HIV， cancer and illnesses at the more severe end of the spectrum. Quite often， we get people who nursed someone through cancer and they become preoccupied with the thought that they have the disease too， or it develops because they have heard or read about someone with the illness.“

　　Health anxiety is characterised by the excessive seeking of reassurance， from doctors or from family members. ”What we always tell people on our helpline is that reassurance doesn’t work，“ says O’Neill. ”I have seen people who have convinced themselves they have a brain tumour – they go to their GP， they go for scans. When they are reassured they don’t have a tumour， they still think what if they missed it? What if it was too small to see? What if this is one of those NHS mistakes? Because the media highlights it so much when things do go wrong， it feeds the feeling in people with health anxiety that ’I could be the one that it goes wrong for’。 People ring up and ask， ’Do you think I’ve got cancer?’ I can’t offer that reassurance because how would I know? But we do know that reassurance only works in the short term. It isn’t long before those fears return.“

　　Another problem， O’Neill says， is that health anxiety – which used to be called hypochondria – is not taken seriously. ”It can be seen as a bit of a joke， but it can have a serious impact on someone’s life.“

　　Mark agrees. ”When you’re in the grip of it， it can be terrifying. It affects all aspects of your life – your work， your relationships – because you can’t think about anything else， and you’re living with this expectation of impending death.“

　　According to Professor Peter Tyrer， head of the centre for mental health at Imperial College London， ”about 1-2% of the population have pathological health anxiety“， and in people who have already had treatment for a condition， it can be around 10%. He thinks the number of people affected is rising.

　　The internet， he says， is one reason. ”Everyone looks up their symptoms， but the internet tells you everything and nothing.“ O’Neill agrees： ”Type in flu symptoms and you will be able to find a huge range of diseases from a common cold to the early stages of an HIV infection.“