Study: Drug Ad Side-Effect Warnings May Actually Boost Sales

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"Side effects may include dry-mouth, insomnia, sexual side effects, diarrhea, nausea and sleepiness," warns the Zoloft ad above. And those aren't even particularly dire side-effect warnings, as drug ads go — some warn of possible blindness, even organ failure or death.

If you've ever wondered why pharmaceutical companies haven't resisted these daunting end-of-ad warnings more, here's a possible piece of an explanation: A new study in this month's issue of the journal Psychological Science finds that the fear sparked by such warnings fades very quickly over time, and may even end up morphing into trust and boosting sales. From the press release:

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

Carmon and colleagues tested their hypothesis in four experiments. In one experiment, for example, smokers saw an ad for a brand of cigarettes: one version of the ad included a warning that smoking causes lung cancer, heart disease, and emphysema, while another version did not include the warning.

Predictably, participants who had the opportunity to purchase the cigarettes soon after seeing the ad bought less if the ad they saw included the warning.

In contrast, participants who were given the opportunity to purchase the cigarettes a few days later bought more if the ad included the warning. The same outcome emerged when the researchers ran a similar experiment with ads for artificial sweeteners.

According to Carmon and his colleagues, the warnings backfired because the psychological distance created by the delay between exposure to the ad and the customer decision made the side effects seem abstract—participants came to see the warning as an indication of the firm's honesty and trustworthiness.

In fact, participants evaluated drugs for erectile dysfunction and hair loss that had potentially serious side effects more favorably, and as more trustworthy, when they were told the products weren't on the shelves yet.


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

Readers, does this ring true? Do you think side-effect warnings end up inclining you more favorably toward a medication?

This program aired on September 25, 2013. The audio for this program is not available.

Carey Goldberg Twitter Editor, CommonHealth
Carey Goldberg is the editor of WBUR's CommonHealth section.