When I use a word . . . What is a physician?

Doctor or physician?I was surprised when I first learnt, some time ago, that in the summaries of product characteristics (SmPCs; previously called data sheets) of certain drugs it is specified that they should be used “at the discretion of the physician,” often when advising about use in special groups, such as pregnant women or children. Surprised, not because advice was required, but because a physician was specifically required, not just any doctor. Indeed, I estimate that the term “physician” occurs 3–4 times more often in such sources than the word “doctor.” Furthermore, the two terms often seem to be being used interchangeably. In at least one case, for example, they were used as if they were synonymous, with advice that the product was to be used “under the direction of a physician” followed almost immediately by the instruction that “if the usual dose [was] less effective or its duration of…