Advertisements for prescription drugs include a list of side effects so that consumers are fully aware of the possible risks. A study recently published in Psychological Science determined that these side effects don’t make people avoid these products, but rather buy more of them.

"Messages that warn consumers about potentially harmful side effects — presumably with the intent to nudge them to act more cautiously — can ironically backfire," said lead researcher Ziv Carmon from the post-graduate business school INSEAD.

Carmon and his colleagues, Yael Steinhart and Yaacov Trope, used four experiments to decide how side effect warnings influence our decision making when it comes to prescription medication. Individuals participating in the study were asked to watch a commercial that advertised cigarettes, artificial sweeteners, or prescription drugs. One ad featured a list of side effects including heart disease, blindness, and cancer, and the other did not include health warnings.

Participants who saw the ad that included side effects right before they were presented with the opportunity to buy cigarettes were less likely to do so. On the other hand, those who saw an ad with a list of side effects and went to buy cigarettes a few days later were likely to buy more.

"We were struck by just how detailed, clear, and scary many warnings had become with regard to potential negative side-effects of products," explained Carmon. "It then occurred to us that such warnings might perversely boost rather than detract from the appeal of the risky product."

Researchers attributed this unexpected finding to a consumer’s trust toward a drug company that lists side effects. Participants in this study were more likely to dispel side effect warnings because they associated it more with the company’s “honesty and trustworthiness.”

"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," Carmon added. "By doing so, they miss out on this worrisome delayed outcome."

Source: Steinhart Y, Carmon Z, Trope Y. Warnings of Adverse Side Effects Can Backfire Over Time. Psychological Science. 2013.