The Internet can be an excellent health resource, if you use it safely. This includes screening out dubious information, using message boards wisely and checking with your doctor before acting on advice.

Who's who. When you're checking out a health site, consider who's behind it. A site run by a university or medical association trumps one owned by the manufacturer of an unregulated supplement because it will probably be based on science rather than a sales pitch. Look for a stamp of approval from organizations such as HONcode (Health On the Net Foundation) or URAC, which certify credible sites. See if a physician has reviewed the medical content.

The "About Us" link can reveal a Web site's credibility. Look for information about the site's medical advisers, executives, ownership, press releases, media profile, mission and partnerships. You can see, for example, if a site has ties with major medical centers, leading researchers or reputable nonprofit organizations. You can also see if a site that appears to be about depression or tobacco addiction is actually owned by a pharmaceutical company that sells drugs for those conditions.

On board for safety. When using message boards and forums, remember that you are in charge of how much information you reveal. Do not post your phone number or email address unless you're willing to hear from anyone who has access to a phone or computer. Do not reveal your information about your health insurance to prevent identity theft or insurance fraud.

Beware of posting seemingly harmless information that actually reveals your identity or location, especially when your kids are using the computer. WiredSafety, an Internet safety organization, gives the hypothetical example of a girl who posts a link to her Web page: "Hi, my name's Jenny and I am 13 years old. I live in Wisconsin and I love cats!" Seems fine, yet that page also links to her mother's cat-breeding Web site, complete with address and phone number.

Deal with your doc. Many patients turn to the Internet for coping tips and information about new treatments. Maybe one of these remedies will finally ease your decades-long battle with pain ... or waste your money ... or kill you. Always check with your doctor before taking medical advice you find online. You might get the go-ahead to try a new therapy, or you might learn about dangerous side effects or a ban from the Food and Drug Administration.

As always, keep your antivirus software updated and don't open spam. After all, when you're trying to get medical information for yourself you don't want your computer to come down with a virus.

More: Learn how to protect your privacy on the Internet.