When Bob Staib of Lexington, Ky. was diagnosed with prostate cancer in 1995, he read an article about the Internet, bought a computer and began to use the Web to educate himself about his disease. Since then, he has discussed the therapies he finds online with his doctor, and together they make treatment decisions. Doctors told Staib he would have five years to live after his diagnosis, but he has been fighting cancer for almost 10 years now. “The Internet has been my salvation,” he said. “I’d probably be dead if it weren’t for that.”

Others have not had the same success. A patient of Dr. Ronald B. Kuppersmith, coordinator of Internet and information technology for the American Academy of Otolaryngology-Head and Neck Surgery, trusted inaccurate information he read online and suffered traumatic consequences. The patient had cancer and refused various treatments after doing research online. “He went from having something treatable to something untreatable even with heroic measures,” Dr. Kuppersmith said. “We tried for one year and could not save him.”

These two examples illustrate the double-edged quality of Web medicine today. While information on the Internet can help patients manage their own care, it can also lead to dangerous decisions. The explosion of health information on the Internet has made regulation difficult, allowing Web sites with incomplete and inaccurate information to persist. Doctors are trying to guide patients through the confusion by discussing the information with them and posting doctor-approved material on professional Web sites. These actions are transforming the traditional face of medicine. They are making doctor and patient partners in health care and gradually pushing medicine into the age of electronic technology.

The number of health sites on the Web has been on the rise since Internet use ballooned in the mid-1990s. Dr.Koop.com, in 1997, and WebMD, in 1998, led the way in bringing consumer health information online. The presence of health information has exploded since then, growing from 10,000 sites in 1997 to an estimated 50,000 to 100,000 sites in 2003, according to Dr. Tom Ferguson, senior research fellow for online health for the Pew Internet & American Life Project.

More and more patients are surfing the Web for health information. Studies rank searching for health information as the third most popular use of the Internet, after e-mail and researching products. Of all adult Internet users, 80 percent, or about 93 million Americans, research health topics online. Most individuals surveyed by Pew claimed that the Internet has positively affected their health and they trust the information they find.

However, numerous studies have shown that, in many cases, patients should not believe the health material they read on the Web. These studies have identified three main problems facing Internet health surfers: inaccurate information, complicated writing style and ineffective search engines.

Inaccurate health Web sites outnumber reliable sites, according to doctors. For example, Dr. Gunther Eysenbach of Toronto General Hospital’s Centre for Global eHealth Innovation and his associates reviewed 79 studies of the quality of Internet health information. In their evaluation of the methods the researchers used to assess the Web sites, they found that only nine percent of the investigations described Internet health information as reliable. Those investigations used lower standards that the other studies. According to a report by Dr. Gretchen Berland and her colleagues at the RAND Corporation for research analysis, more than half of Web health sites contain conflicting material. For example, they discovered a childhood asthma Web site that in one area reported that inhaled steroids stunt children’s growth and then in another area that they do not. Many sites are incomplete, ignoring half of the topics doctors considered essential for visitors of the particular site, Dr. Berland and her associates reported. For example, few sites that discussed suicidal thoughts advised people having these thoughts to “seek care promptly.”

The complicated terms and long sentences health Web sites use often confuse people, leading them to trust information precisely because they cannot understand it, according to Pew. Those surveyed said that they assume Web authors must know what they are explaining when they use complicated terms, just as the sprinkling of technical words in conversation can make anyone sound like an expert. The average reading level of Internet health information was high at 13.2, the level on which a college freshman should be able to read. Pew reported that the average consumer reads on a much lower reading level, sixth to eighth grade, making most health information too difficult for them to fully understand. Marketers write most consumer materials on a seventh- to eighth-grade level.

The all-purpose search engines, such as Google and Yahoo!, and the simple terms most patients use to search for information do not lead them to high-quality health Web sites. Only 35 percent of sites identified by these engines were based on proven, scientific claims and did not endorse a product, according to research published in August of 2003 by Michael Slater and Donald Zimmerman of Colorado State University’s Department of Journalism and Technical Communication. A significant number of promotional sites, 20 percent, touted unproven treatments, and some of these included “pseudoscientific claims” that may mislead even readers with college-level scientific education. An additional investigation found that less than one-quarter of the first pages of links displayed by search engines led to relevant sites.

Patients find it difficult to wade through these search results and locate the useful sites. “People have to make on the fly decisions about what’s on the screen in front of them,” Slater said. Whether or not the site advertises a product and who sponsors the site are crucial indicators of the objectivity and reliability of the site. However, patients often cannot get this information from the search listings, Slater and Zimmerman’s study found.

Given the abundance of health information on the Web, its variable quality and the inadequacy of popular search engines as navigators of this information, patients frequently have trouble finding reliable material. “There’s a bit of a free-for-all on the Internet right now,” said Dr. Scherger. “It’s as if all print material looked alike, such as The National Enquirer and The New England Journal of Medicine.”

The sheer mass and amorphous quality of the Internet make regulation very difficult, according to Dr. Slater. Many physicians say regulations will never selectively prevent health content from being posted on the Web, as that could impinge on the source’s right to freedom of speech. For now, agencies only regulate overtly dangerous health information that runs counter to laws protecting consumers, regulating drugs and preventing fraud, “letting the buyer beware,” as Dr. Kuppersmith explained, in all other cases. Dr. Thomas Bodenheimer, a professor of family and community medicine at the University of California at San Francisco, said the Internet has much to offer patients, but it should be regulated. “It’s just absurd, this whole freedom of speech thing,” he said. “It’s okay to lie to people?”

A few organizations, such as URAC and HONcode, currently rate health Web sites in an attempt to inform consumers about information quality without taking away an individual’s freedom to post information online. Neither organization, however, vouches for the reliability of the information on the sites they approve. Nicolas Terry, a professor of law and co-director of the Center for Health Law Studies at St. Louis University, is skeptical about the efficacy of these rating systems. The Web is dynamic, changing constantly. Rating organizations claim to periodically review approved sites, but they cannot constantly keep tabs on them.

Without effective guidelines or widely used rating systems as recourse, individual providers and larger health care organizations, such as Kaiser Permanente, are taking the problem of Internet misinformation into their own hands. More than 80 percent of patients who use the Web use it as a supplement, not a substitute, for visits to their health-care provider, according to Pew. As a result, patients can use face-to-face visits to discuss material they have found, as Bob Staib does, and their doctor can help them distinguish between accurate and inaccurate information. The American Medical Association recommends that Internet users treat information on the Web with the same skepticism they treat print publications. Patients should pay attention to the source of the information, citation of references, disclosure of competing interests, and timeliness of the information. Currently, however, one-half of Internet users ignore these important cues, Pew reported.

Doctors, such as those at the Mayo Clinic, are also trying to police Internet health information by posting health material on their own Web sites. This movement would increase the availability of Web health care information already vetted for content. Commenting on this trend, Dr. Daniel Sands, a professor at Harvard Medical School, said, “I hope in five years we get to the point where it is malpractice to practice without electronic technology.”

Dr. Scherger compared the increase in medical providers’ use of the Internet to the evolution of online backing, with most banks now having Web services. “Once people get used to this service, all health-care providers will also have to do it,” he said.