Consumer advertising for prescription drugs had a negligible impact on sales of products studied by Harvard Medical School researchers — in a finding that may confound both advertisers and their opponents. The study may undercut the arguments of opponents of such ads, which have been allowed almost nowhere outside the U.S. Critics say they lead to drug overuse and misuse by impressionable patients pressing their doctors to prescribe what is seen on TV. But the study also raises the question of whether the pharmaceutical industry’s $4.8 billion annual spending on such ads is a waste of shareholders’ money. The U.S. Food and Drug Administration, which loosened its regulations to widely permit such ads in the 1990s, is under pressure to tighten its rules and has announced it will study the issue. Meanwhile, the European Union, which bans consumer ads, is considering a proposal to loosen its rules. In Canada, where ads are also banned, a court battle could lead the government to allow them. Other studies have found that direct-to-consumer advertising of drugs does raise sales. But the new study will draw some attention because it is among the first to compare the behavior of people […]