Searching the web for medical information can be tricky becasue of the abundance of not-so-good sources of information. Find the good stuff! Look for sites that have the following qualities:
1: Reviewed by Others: Another reputable person or agency (library, journal, organization) has reviewd the website and determined that it is valuable.
2: Hosted by a Reputable Source: Such as a government agency or prominent research institution/university/college.
3: Gives References: Where did their information come from? They should cite it!
Check out the Stop! Evaluate Websites Before Use guide for more tips and tricks on evaluating websites.