I think that many of us from the US, and maybe other places, are surprised to find how much independence and authority pharmacists in Spain have. I would say they are much more in the category of "respected professionals" than they are in the US. That means that they use their own judgment more, which means more flexibility in how they adhere to the rules. For the rule-bound forum member, this is not a good thing, for those of us who sometimes find ourselves in an unexpected medication pickle, it's a good thing. Though this may be changing, as a foreigner, I have never had a problem getting prescription medication, with or without a prescription. Knowing what medication I need, and being able to describe what it is for and why I need it now, have always been enough to get my medication.
A few years ago, in Oviedo, I met a young American who had run out of anti-depressants and had no prescription. I went with him to a pharmacy and explained his situation. The pharmacist was extremely helpful, looking up his medicine (they have different brand names so knowing the active ingredients may be crucial), and told me it was her professional duty not to cause harm, which is what certainly would have happened if this guy couldn't get his meds.
It's always a good idea to have the prescription with you, but know that in a pinch, you are likely to be ok without it. Buen camino, Laurie