When it comes to TV commercials for medications, we're all familiar with the mile-a-minute speech toward the end, listing the possible side effects. We assume any doctor could reiterate the same side effects during an appointment. But a new study has shockingly shown that many doctors don't know many of the side effects of the drugs they are prescribing to patients.

In four cities, Vancouver, Montreal, Sacramento, and Toulouse, physicians were selected at random. Of the 704 doctors contacted, 36 percent participated in the poll. The researchers then gathered information about 1,692 drugs that were promoted by pharmaceutical drug reps between May 2009 and June 2010. After drug reps had visited the doctors, they were asked to fill out a questionnaire that tested their knowledge of the drugs' benefits and risks and to assess how these drugs were promoted.

The results from the study were a bit dreadful, showing that doctors were left ill-informed and that pharmaceutical representatives failed to tell the whole story when talking about medications. Drug reps concentrated on the benefits of drugs more often than the risks in all locations in the study. In fact, in the majority of visits to doctors, or 59 percent of the time, representatives did not mention any adverse side effects of drugs at all. That percentage rose to 66 percent in Vancouver and Montreal. This is disturbing, as two-thirds of doctors reported that they were more likely to prescribe medications after a product was promoted by a rep.

The therapeutic benefits are highlighted in 80 percent of cases and side effects in only 40 percent.

On the flip side, in France, drug reps mentioned adverse reactions 61 percent of the time, but the global average remained abysmal at 41 percent. This an interesting result, given that France holds a history of Sanofi drug representatives lying to doctors and badmouthing generic versions of Plavix. They would consequently put doctors at risk for lawsuits. In the end, however, Sanofi representatives themselves were fined for such actions.

Source: Mintzes B, Lexchin J, Sutherland JM. Pharmaceutical Sales Representatives and Patient Safety: A Comparative Prospective Study of Information Quality in Canada, France and the United States. Journal of General Internal Medicine. 2013.