Warnings of serious side effects in drug advertising can actually improve consumers’ opinions and increase sales, rather than frightening them away, new research finds.

Ads may include warnings of side effects ranging from nausea and bleeding to blindness and even death, but they can improve consumers’ opinions about the product when there is a delay between them seeing the ad and deciding to buy or consume the product, say the researchers, reporting their findings in the Association for Psychological Science journal Psychological Science.

“Messages that warn consumers about potentially harmful side effects, presumably with the intent to nudge them to act more cautiously, can ironically backfire,” comments psychologist scientist Ziv Carmon of INSEAD in Singapore, who conducted the research with Yael Steinhart of Tel Aviv University and Yaacov Trope of New York University.

Examining how adding a warning of potential side effects affects consumer decision-making, the researchers say they have been struck by just how “detailed, clear and scary" many warnings have become with regard to potential negative side effects of products.”

“It then occurred to us that such warnings might perversely boost rather than detract from the appeal of the risky product,” said Dr Carmon.

The authors believe that warnings backfire because the psychological distance created by the delay between exposure to an ad and the consumer’s decision makes the side effects seem abstract, and that the customer actually comes to see the warning as an indication of the firm’s honesty and trustworthiness.

In fact, participants were found to evaluate drugs for erectile dysfunction and hair loss that had potentially serious side effects more favourably, and as more trustworthy, when they were told the products were not on the shelves yet.

While conventional wisdom suggests that explicit warnings about dangerous side effects will make people think twice before taking medical risks, these results suggest otherwise, say the researchers. And this is important because these kinds of warnings are so ubiquitous, accompanying so many different products or services beyond medications, that greater attention should be paid to their potential to backfire, they add.

“This effect may fly under the radar since people who try to protect the public – regulatory agencies, for example – tend to test the impact of a warning shortly after consumers are exposed to it. By doing so, they miss out on this worrisome delayed outcome,” said Dr Carmon.