No, stupid and careless doctors know nothing about drugs. Any competent physician, before prescribing anything, will a) ask the patient what medicines (and recreational drugs even) they are currently taking and b) cross-check the medicine for contraindication - like the nasty effects you get when mixing serotonin suppressors and enhancers - serotonin syndrome would not be fun. Doctors and dentists have a huge horking book called Physicians Desktop Reference or the PDR. The PDR has in it almost every prescription drug in existence - structure, dosage, pictures, and its side effects. If they're competent, they'll check medications if they haven't memorized the relevant information already.

They also won't proscribe antibiotics for a cold, no matter how much a pushy patient asks for a placebo. And to be fair, the majority of antibiotic use in this country is not human patients - it's animals. Animal antibiotic use is almost a bigger problem than human.