Is it possible to diagnose medical symptoms through the Internet?

Several websites, including WebMD, Isabel and Mayo Clinic, offer free online symptom checkers. Each of these resources stress that online diagnosis is no substitution for an in-person appointment with a licensed physician, which is the most accurate and reliable way to receive a medical diagnosis.

The WebMD symptom checker walks a patient through a series of increasingly specific questions before arriving at a list of possible ailments, based on the symptoms described. Similarly, the Mayo Clinic symptom checker prompts a patient to choose from a list of common ailments and, by asking additional information regarding that condition, provides a list of possible diagnoses. Mayo Clinic's symptom checker alphabetizes its results and divides them into ailments common to adults and ailments common to children.

Isabel boasts a symptom checker used by physicians. Isabel prompts a patient to enter basic information about his ailment and then lists probable diagnoses. To learn more about these conditions, Isabel directs patients to external websites such as Wikipedia.