The head of the general practice department at Otago University, Christchurch, Professor Les Toop, said self-diagnosis was not new as people had previously gone to libraries to look up their issues.
He said on-line diagnoses could be helpful, but he cautioned against over-reliance on the internet.
"It is a completely unregulated environment ... some of the information is good, some of it's not and some of it is driven by advertising and sales."
He said he didn't have a problem with websites that offered solutions for people with minor irritations.
"Where it would be [a problem] is where people are trying to diagnose themselves for having haemorrhoids when they have got bowel cancer."
Medical Association chairman Mark Peterson said self-diagnoses on the internet were among the biggest Google search categories, and were sometimes helpful in arming patients with more information when they went to visit their GP.
Southern Cross Healthcare Group chief executive Ian McPherson, a former GP, said it was was not surprising people were turning to the internet given the wealth of information available online.
The national TNS survey showed those most likely to search for health information online were people living in Wellington and Tauranga, females and those under 50.
Self diagnosis
55 per cent of Kiwis use the internet to research ailments
22 per cent do so at least once a week
9 per cent discuss findings with GP
7 per cent self-diagnose but don't seek treatment.
