As with any content on the Internet, assessing the credibility of online medical advice comes down to evaluating the source of the information. Although the Internet can empower you with the latest health information or help you find people who are going through the same medical issues -- proceed with caution.

For example, sites that are known to be reliable and are backed by offline medical experts include WebMD, the American Medical Association, DrKoop (a site by the former U.S. Surgeon General) or Health Central, which features popular experts, including Dr. Dean Edell.

However, other so-called medical advice sites on the Internet often are produced by drug-makers -- and there's no way of knowing if their products have received FDA-approval -- or feature alarming, unsubstantiated information that can make you worry even more.

When in doubt, go to web sites created by the same trusted sources you'd turn to offline. And always get a second opinion: When seeking advice or researching medical issues, check out at least two non-profit or well-known health organization's sites and then run whatever you've learned by your real-life physician.