Although the internet has given anybody with a computer access to a seemingly limitless amount of information, it has also had a profound effect on clinical medicine--and not necessarily a good one.

Doctor's writing in the New England Journal of Medicine say that patients are often exposed to incorrect or poorly interpreted information on the internet that is fundamentally changing the "the core relationship between doctor and patient."

While applauding the ability of patients to receive test results and communicate with their clinicians electronically – and to search for disease symptoms at numerous web sites – the authors suggest it is a journey no patient should undertake alone.

"Material is perceived as factual merely because it is on a computer screen. We sometimes find ourselves in the uncomfortable position of trying to dissuade desperate and vulnerable patients from believing false testimonials," they write.

"Falsehoods are easily and rapidly propagated on the Internet: once you land on a site that asserts a false rumor as truth, hyperlinks direct you to further sites that reinforce the falsehood."

They cite the example of a neighbor, with a tendency toward hypochondria and with web access, who fretted that a backache was actually an abdominal aortic aneurysm.

"After a week of self-palpation, he mustered the courage to call the doctor. With a normal exam and repeated reassurance, the backache resolved."

The editorial also warns that secure web portals where patients can remotely view their laboratory, radiology and pathology reports can be a double-edged sword.

"This technology is efficient, averts the need for multiple phone calls and the mailing of information. The benefits though, must be weighed against potential negative effects of receiving clinical data without context. Patients and families may be confused by results and worried that minor abnormalities might portend serious consequences."

Most important, however, is the reality that the Internet simply cannot substitute for human interaction.

"It's impossible to judge the effects on patients of information transmitted through cyberspace: we can't observe grimaces, tears and looks of uncertainty. And written dialogue is quite different from spoken conversation: replies may be delayed, phrases may be more stilted, tone of voice is absent."

"Knowledge is said to be power and some of the past imbalance between patient and doctor may be equalized," they write. "But information and knowledge do not equal wisdom, and it is too easy for non-experts to take at face value statements made confidently by voices of authority.

"Physicians are in the best position to weigh information and advise patients …The doctor, in our view, will never be optional," the doctors say.

Citation: Pamela Hartzband, Jerome Groopman, 'Untangling the Web — Patients, Doctors, and the Internet', NEJM, March 2010, 362:1063-1066