Health care professionals likely know and use the online resource UpToDate. I have been using it since I was a resident, and maybe even as a med student. At any rate, I remember when it was on CDs. And I remember when there were no online resources and we had to look up journal articles in an index book, but I digress. . .
We have an institutional subscription at my office and hospital and I use this resource frequently. I have just learned over at 33 charts that there is now a patient site online. Find the patient information site here.