As much as we'd like to think Mario is an accredited doctor with the papers to back it up (that University of Phoenix diploma above might as well be toilet paper), the dude is just a plumber in a white lab coat. Unlike most practitioners, he's willing to throw pills at any problem and can only really deal with two issues: the chills and fever. Nothing makes this more evident than the video made by College Humor user Brentalfloss, which adds lyrics to the Dr. Mario theme ... and some kinda disturbing imagery, too. Check it out at your own risk!
Source - Dr. Mario with Lyrics (probably NSFW)