The marketing of medicine in inherently unethical because it seeks to override doctors and consumers information-based evaluations, and instead make a choice based on emotional propaganda. The harm caused by any given medical advertisement is directly proportional to its effectiveness. Every pharmaceutical sales rep is an immoral cancer on our society.
Ad supporters will sometimes say that ads are meant to get the word out about a product so people know its an option. How can we prove that this is false or that the benefits are smaller than the drawbacks?
Find a natural experiment where two very similar populations, chosen at random, were placed into two different cohorts. I'm sure there's one somewhere in the recent and well documented past.