Dr Google, MD

From thyroid inflammation to chronic illness, more and more people re diagnosing themselves on the web. Doctors, however, caution to tread carefully.

Kate Harris was in agony, again. The 28-year-old events manager had been thrilled when a job offer in the UAE promised an exciting new life for her, but just three months after relocating from the UK to Dubai, she woke up unable to speak, a familiar, searing pain radiating through her mouth and throat.

Harris suffers from chronic mouth ulcers, a condition that she has struggled with since her early teens. While it is common to get an occasional, painful blister that can be coaxed away with over-the-counter remedies, her mouth fills with clusters of stubborn ulcers at the slightest sign of stress. A new job, hectic deadlines and the worries of uprooting from one country to another had taken their toll, and Harris fled to her nearest pharmacy in tears. "The pain was horrific. Just imagine a mouthful of exposed, raw nerves, that kind of intense pain. They suggested I try mouthwash, or see a dentist, but I knew from past experience that this wasn't going to help me, as I'd suffered for years after being told the same thing over and over again. That was when I realised I can't be the only person who suffers like this. I went on the internet to find help, as I couldn't go on like this."

Harris is one of a growing number of millions of people around the world who turn to the internet for help with self-diagnosis. It's an area that has spawned a huge growth industry, from websites sponsored by drug companies to grassroots forums to government-funded resources. Patients can research peer-reviewed medical papers at the same time as meeting fellow sufferers. Doctors are also using the web to search for up-to-the minute research that might otherwise take months to filter down through word of mouth or industry publications.

A survey released this month by Britain's Department of Health says nearly one in six people in the UK have used the internet to self-diagnose instead of going to see their GP. Self-diagnosis is most common among 18 to 24-year-olds, with a quarter of this age group going online to solve their medical problems. Not everyone thinks this is a good idea. "While it may feel like a quick-fix solution, using the internet to guess your medical prognosis does not compare to seeing a medical professional with years of training and experience," says Dr Mike Warburton, the national director for GP access at the UK's Department of Health.

The internet isn't subject to the same stringent fact-checking that applies to more traditional sources of information such as medical textbooks. But it is an appealing gateway for those too busy, or too embarrassed, to see their family doctor. "I looked online when I started getting symptoms," admits Komal Patwari, a restaurant manager who was too busy to see her doctor in Dubai. "But the searches on these websites can tell you that you have anything from an allergy to a bone disease. People should definitely see a doctor - they're obviously around for a reason."

Misinformation, which spreads online just as quickly as verifiable fact, can cause patients to bolt down dead ends and chase false leads while their health remains in jeopardy. Doctors don't always appreciate having their judgement called into question, either. Dr Sean Petherbridge, a family medicine specialist at Dubai's Infinity Clinic, says searching for answers on the internet can be a double-edged sword if not done carefully. "Diagnosing online helps as a good starting point, and it's great for minor ailments such as how to dress a simple wound. The danger is when patients convince themselves they have a rare condition. I see that all the time; they come in saying they think they have thyroid problems or anaemia, and it's often just tiredness and fatigue."

But the internet isn't always misleading. Jane Michaels, a mother of one, says that looking online brought her straight to the root of her problem when she self-diagnosed a thyroid disorder last year. "I was planning to go to a doctor when I noticed a swelling in my neck but I thought I'd Google it first and see if I could figure it out for myself. I used a mixture of reputable-looking medical sites as well as online forums where people, many of whom seemed like hypochondriacs, compared notes on their issues. I figured out that my thyroid gland was swollen."