There is no doctor in your computer able to divine your illness from a vague list of symptoms.
That's the message for people who try to figure out what's wrong using computer search engines, new Australian research shows.
Whether it's "sharp pain in my finger" or "strange rash on chest", searching about our heath is something we've all done online.
Google estimates one in 20 of its 100 billion searches each month is someone looking for health advice and information, and the quality of material available on specific conditions has improved over the past few years.
However, a study from the Queensland University of Technology has found search engines are very bad at directing people to accurate information when they type in common language descriptions of their conditions.
Guido Zuccon, from QUT's Information Systems School, tested eight common descriptions of conditions against Google and Bing searches, and concluded search engine results could be putting people's health at risk.
"There were cases where the information was just not useful for the person," Dr Zuccon said. "But it's the web pages that were suggesting something that is just not what you have, or are trying to sell you something and is saying 'you have this and this is how you should treat it', that's when our very big concerns arise."
The researchers examined eight main conditions and several common descriptions of those conditions; for example, "extreme red rash on arm" for hives (technically called urticaria), or "puffy sore calf" for oedema.
They found only four or five of the first 10 results on a page would be useful for the person doing the search. Only three out of 10 were highly relevant.
"A large number of irrelevant documents did contain the query terms but were suggesting a different medical symptom than that underlying the issued query," Dr Zuccon and his co-authors from the CSIRO and the Vienna University of Technology wrote in a paper delivered at the European Conference on Information Retrieval.
At best, the advice could simply be misleading and, at worst, it could do them harm by giving them a false sense of security or directing them towards ineffective treatments, he said.
"Search engines are just not reliable at the moment for these types of information searches," Dr Zuccon said.
He said search companies had gone some way towards ensuring that when someone searched for a specific condition, such as coeliac disease or breast cancer, they would get accurate and reliable responses.
However, they were not equipped to know from a few words what an individual was experiencing.
"You have to remember that search engines work by retrieving information that has already been talked about. And if the information is not there, you can enter as much information as you want and it will never be able to retrieve what you need."
In the end, it doesn't matter how many gory images of other people's rashes you look at, the only person who can diagnose what you've got is your doctor.
The story Dr Google: Why googling symptoms doesn't diagnose your disease first appeared on The Sydney Morning Herald.