They're a GP's nightmare - patients who've diagnosed themselves on the web. A little knowledge can be a dangerous thing, says Steve Curtis

Patients used to be a compliant lot. They'd come in, list their symptoms, and listen attentively to the wise advice the doctor would give them.

Nowadays, all too often, they come in, root around in their bags, produce a sheaf of print-outs from the internet and proceed to instruct you as to the best way to treat the condition they have convinced themselves they've got.

All across the planet, physicians are finding themselves confronted by the modern "heart-sink" patient; the one with a little knowledge. Quite recently, one of my own patients took me by surprise by quoting a relevant medical fact, and I found myself asking whether he had a medical degree. "No," he told me, without cracking a smile. "I've got broadband."

What usually follows is a burst of disarming intelligence followed by a seamless lapse into gibberish. The first time I heard it, I felt this odd sense of déjà vu. After a while, I realised why; there have been several occasions in my career when I've been called down to A&E to see people who've managed to injure themselves in a manic state. The conversation that follows starts out OK and then - suddenly - it dawns on you that they've lost it.

Broadly speaking, hospital specialists (such as myself) tend to be less fazed by the internet-savvy patient than our colleagues in general practice. It's actually quite hard to outpace a career endocrinologist just by spending a couple of hours on Google. In contrast, one GP friend of mine readily admitted to finding the internet useful himself, citing a couple of web pages: and

This was worrying. I started to wonder if doctors were just another endangered species. Then, as if to add insult to injury, a new and original research paper emerged from Australia, published in this week's British Medical Journal, where a group of chest physicians had experimented in making diagnoses by Google. They used real cases, but for research purposes were unaware of the true illnesses. They keyed a number of details from the cases into Google and then selected the most prominent diagnoses that seemed to fit the symptoms. It turned out that they'd been right in a staggering 58 per cent of cases.

It's hardly surprising that your average patient believes he can circumvent the medical profession altogether. Another GP friend of mine found himself confronted by a patient with a print-out that he simply refused to accept might be wrong. "It was a really smart-looking website, but it mixed up the antidepressant bupropion with bupenorphine, which is an opiate detox drug for narcotics users. Pathetic!"

The GP fished out a paperback copy of the BNF, the standard doctors' reference for drug names and doses. Disturbingly, the patient remained convinced that the doctor and the BNF were wrong and he was right. After all, he reasoned, books are old-fashioned things. If it was on the internet, he said, it must be true.

The big problem for the amateur doctor is his inability to distinguish between the common and the uncommon. As a former medical student myself, I can sympathise. How much more satisfying it is to diagnose yourself, or someone else, with an exotic tropical infection, picked up against the odds in the arrivals lounge at Heathrow, rather than just, well, a nasty cold. While the internet contains plenty of good sense, some of it is little more than pseudo-science. Some patients become convinced that salvation lies in a completely alternative - and probably worthless - remedy.

Still, not everybody in the medical profession seems bothered by this trend. One consultant colleague recently admitted: "I used to be pretty scathing of these people who come with half-baked alternative treatments, but now I've changed my view. If someone turns up and says, 'I stuck this Mongolian magnet to my knee and now my pain's gone away and I don't need a knee replacement any more,' then good for them. Just quietly take their name off the waiting list and call in the next patient."

Eager to see if this attitude was more widespread, I asked another former colleague how many of his patients had managed to research their conditions on the internet. "None at all," he told me, without having to think about it. As if in explanation, he added: "I work in a psychiatric rehabilitation unit."

It would be misleading to suggest that schizophrenia selectively picks off people from the bottom of the social spectrum, but once afflicted, many patients often slide rapidly down the social ladder. Few, if any, will have access to the internet, let alone the inclination to use it. And here we see a recurring theme in every doctor's account of the internet; it attracts a lot of attention from the "well worried" educated middle classes who, by their very nature, are less likely to be ill in the first place.

The reality is that the web-surfing population is probably healthier than the non-web-surfing population. People who use the internet are themselves a select group. Motivated, often eager to return to satisfying, well-paid jobs, these people are less likely to smoke, less likely to work in a physically dangerous environment and much more likely to be a member of the local gym. A colleague who seemed to have worked in every corner of Birmingham says he has only really been petitioned with web print-outs in one district, Solihull - Birmingham's answer to South Kensington.

As a surgeon, when I'm trying to write professional research papers, I'm extremely conscious of which journal I'm going to publish in. If you browse through the peer-reviewed journals for long enough, there is an undeniable gradient of credibility and sophistication between them.

By contrast, the internet is an unregulated medium whose principal function seems to be the popularisation of pornography. Some of the more specialised medical documents downloaded have been written by profit-making organisations with the specific objective of achieving a sale. Even more extraordinary is the eagerness of many patients to believe what they read on the net more readily than they will believe the doctor.

People who have never stitched up anything in their lives are stipulating what kind of sutures they would like in their wounds. It is truly astonishing how many people have figured out in advance what sort of hip replacement they want, including the people who turn out to have nothing actually wrong with their hips.

If the hospitals are paying attention to these people, then the pressure on drug-makers to get their patient-friendly web pages up and running must be immense. At this rate, one can imagine the very same drug reps who have been harassing my colleagues for decades relocating to outpatient waiting-rooms and promoting their products from there.

Dr Steve Curtis is a pseudonym. The writer is a hospital doctor