http://e-patients.net/archives/2013/...gh-search.html

From the article:

"Go ahead and type in virtually any health or mental health condition into Google. Heck, even try a popular medication or two.

Time and time again, you’ll notice a reliable trend — 2 or 3 of the top 10 search results are nearly always going to be WebMD.

Why does WebMD consistently and reliably get so many of their websites into the top 10 or 20 search results for virtually any health condition? That means that what you’re getting is not 10 unique results, but only 7 or 8 results that aren’t WebMD. I don’t think most people visiting Google appreciate that this is even happening."