(MONEY Magazine) – Last year, Veronica Rippe was trying to do her own research on a debilitating kidney infection that didn't seem to be responding to the antibiotics her doctor had prescribed. Logging on to the Net, she typed in a few keywords: pain, fever, kidney, cyst. The search engine turned up a half-dozen websites--all, alarmingly, on polycystic kidney disease, described as potentially fatal. In tears, Veronica called her doctor, who told her, "You do have a serious problem, but it's not polycystic kidney disease and you're not going to die."

Tara DelGado, a lawyer and new mother in New City, N.Y., was suffering from a fever and sharp pains in her side one evening in November 1998. Her brother-in-law urged her to go to the emergency room right away, but she wanted to wait until morning--until he went online and found a checklist indicating that Tara might have appendicitis. Later that night, she underwent an emergency appendectomy.

Moral of the two stories: Medical information on the Net can scare you to death--or it can save your life.

Whether you're trying to quit smoking or research a catastrophic illness, the Internet is now the place to go. In 1999, 34.7 million people sought medical information on the Web, double the number in 1998, according to Cyber Dialogue, a Manhattan firm that tracks Internet usage. There are at least 15,000 health sites, and more are springing up all the time.

As rich a resource as the Web may be, it's also totally disorganized, which means a search can be rewarding or frustrating, depending on your skill (and luck). To make matters worse, info on the Web isn't checked for accuracy or timeliness. So how do you figure out where to go? Over six weeks we scanned hundreds of sites and interviewed dozens of experts on the ins and outs of nonprofit and commercial sites (which run ads and sell goods and services). Here's what we found.

1 FOR GENERAL HEALTH INFORMATION, THERE'S NOTHING LIKE THE WEB.

For the 68% of e-health consumers in the U.S. who classify themselves as healthy or "the worried well," the Web is fantastic: You can get more detailed advice on exercise, nutrition, health habits and bothersome conditions (think poison ivy or insomnia) than your physician would ever have time to give you. Start with a major omnibus site. Our favorite: Mayo Clinic Health Oasis (www.mayohealth.org), affiliated with the world-famous clinic. The site features medical news and Q&As on common treatments and conditions, and lets you e-mail questions to its staff doctors and dietitians.

The best of the major commercial sites is CBSHealthWatch (www.cbs.healthwatch .com), the consumer version of the Medscape site for medical pros. You can scan topics that interest you or join discussion groups on specific diseases. Another good first stop: the Merck Manual (www .merck.com/pubs/mmanual). Merck, which publishes this doctors' reference book on a not-for-profit basis, has also put parts of the plain-English Merck Manual of Medical Information--Home Edition online (www.merck.com/pubs /mmanual_home).

2 IF YOU'RE FEELING SICK, THE WEB IS NO SUBSTITUTE FOR A FLESH-AND-BLOOD DOC.

Use the Web to get background info and to help you frame questions for your doctor--but don't delay calling a live medical pro if you're not feeling well.

Online doctor visits may be the way of the future, but for now they're more of a curiosity. Take AmericasDoctor.com (www.americasdoctor.com), whose claim to fame is its free private chats with physicians. Logging on is easy; knowing whom you'll get is not. Our doctor's tag was AmDoc113. When asked about a cutting-edge treatment for chronic eczema, No. 113 had not heard of the treatment. When asked if we should seek a second opinion, the reply was, "That is always a possibility." Well, yes.

At CyberDocs (www.cyberdocs.com), M.D.s serve up diagnoses based on online-chat appointments and even issue some prescriptions (primarily refills and "lifestyle" drugs like allergy medicines). The price: $50 to $100. They also recommend follow-up visits with your own physician. A full complement of specialists is not available in all states, and scheduling an appointment is confusing.

3 MAKING YOUR SEARCH SPECIFIC ENOUGH TO BE USEFUL MAY REQUIRE A DOCTOR'S DIAGNOSIS.

The Web is a wonderful tool to research a catastrophic illness or a complex condition. But type, say, "diabetes" or "cancer" into a search engine and you'll be swamped. "People get frustrated and give up," says Colleen K. Lindell, R.N., co-author of Internet Medical and Health Searching and Sources Guidebook. To keep your search in control, follow these steps:

--Learn about the exact area of anatomy you're interested in.

--Read a few layman's articles for general background and relevant terms.

--Refine your search. A google.com search for "breast cancer," for example, yielded 85,000 results. However, using the "search within" function and adding "postmenopausal" and "stage" and "therapy" produced a more workable 295.

--When you're ready for hard-core medical info, search the Hardin Meta Directory (www.lib.uiowa.edu/hardin/md), a massive but well-organized site for professionals run by the University of Iowa.

4 THERE ARE TONS OF ALTERNATIVE-MEDICINE SITES--AND PLENTY OF QUACKERY. If you're interested in alternative medicine, you'll strike gold on the Web. But the conventional medical world's demand for precision and accuracy is not always shared by alternative practitioners, who often rely on testimonials and folk wisdom in lieu of costly clinical studies.

Be especially skeptical of sites run by nutritional-supplement companies, warns Dr. Stephen Barrett, a retired psychiatrist and proprietor of the nonprofit site Quackwatch.com. Among Barrett's red flags for "quacky" sites: those that say everyone must take vitamins, that losing weight is easy or that fluoridating drinking water is dangerous.

Dr. Herbert Benson, founder of the Mind/Body Medical Institute at Harvard University and author of The Relaxation Response, says if you believe what you read about alternative remedies, that itself might make you feel better--the placebo effect can kick in. "We often denigrate our self-healing powers," Benson explains. "We give more credence to the power of the herb we're using than to our belief in the herb." However, he adds, "if your headache is a brain tumor, you sure want a physician telling you that."

One comprehensive alternative site to check out is HealthWorld Online (www .healthy.net), a for-profit site that offers reports on topics like Chinese medicine and biofeedback. Some reports, though, cost a few dollars. The ever-popular Dr. Andrew Weil (www.askdrweil.com) dispenses advice gratis on a range of holistic and alternative therapies while keeping one eye on conventional, science-based medicine. The nonprofit World Research Foundation of Sedona, Ariz. (www.wrf.org) collects information on alternative treatments, ranging from herbs to color therapy, from around the world.

5 USE INTERNET RESEARCH TO OPEN A DIALOGUE WITH YOUR DOCTOR.

These days, doctors are seeing more and more patients who have done their own research. Most physicians have gotten used to it. Don't hesitate to ask what all your treatment options are, or to raise questions based on your searches--you may have turned up something your doctor missed. If you find a specialist who's doing important work, ask your doc for an opinion--and possibly a referral. But be sensitive; it's counterproductive to slap reams of printouts on your already overworked doctor's desk and demand that he or she read them then and there.

6 DOUBLE-CHECK ALL INFORMATION BEFORE YOU BELIEVE IT.

The August 1999 issue of the medical journal Cancer ran this shocking report: Of 371 websites about Ewing's sarcoma (a rare bone cancer), 42% contained medical information that had not been subjected to stringent scientific review. Six percent contained outright inaccuracies, including one belonging to the Encyclopaedia Britannica, which stated that the disease had a mortality rate of 95% (the error has since been corrected); most medical experts project a survival rate of 70% to 75%.

Your best guarantee of accuracy? Finding corroborating information on two or more sites. And if a site has been proved wrong a few times, remove it from your list of bookmarks.

Also, follow an old journalist's rule and take the source of your information into consideration. Does a website steer you to a peer-reviewed medical journal, a litany of testimonials or a thinly disguised sales pitch? If there are commercial interests, are they clearly disclosed? Is there a respectable medical advisory board? Or a seal from a voluntary organization, such as Health on the Net, that requires adherence to quality guidelines?

Bear in mind too that most medical information has a shelf life of only about five years. A good site usually notes the date of the research it publishes and when the site was last updated.

7 YOU CAN COMPROMISE YOUR PRIVACY WITHOUT REALIZING IT.

Don't click on that banner ad asking how often you go to the bathroom unless you want to start getting mailers about prostate exams. Any personal data you enter on a website "could be captured by someone that you don't want to have it," warns Dr. Donald Palmisano, co-chairman of the American Medical Association's task force for privacy and medical confidence. Don't enter any personal information unless it's encrypted and the site's privacy statement promises not to sell data about you or contact you with unwanted offers.

8 DON'T ASSUME THAT BUYING DRUGS ONLINE WILL SAVE YOU MONEY.

Online pharmacies, which dispensed an estimated $17 million worth of prescriptions in 1999, can save you time and money. Maybe. A University of Pennsylvania study published in the Annals of Internal Medicine last December found that Viagra and Propecia cost 10% more online, on average, than they did at five Philadelphia pharmacies. Researchers Dr. Bernard Bloom and Ronald Iannacone found sites that gave prescriptions on the strength of an online questionnaire; nine of the 46 surveyed sites, all overseas, required no prescription at all.

Avoid sites that sell drugs without a prescription, don't provide a way for you to ask questions of a registered pharmacist or don't provide a U.S. address and phone number. You can check an online pharmacy's credentials with the National Association of Boards of Pharmacy (www.nabp.net; 847-698-6227).