Pharma Paradox: The More Side Effects Listed in a Drug Ad, The Safer It’s Perceived to Be

In direct-to-consumer (DTC) ads, pharmaceutical marketers are required to present all possible side effects of the drug, but a new study suggests that this may be influencing people’s perception of the safety of that medication in a surprising way. Researchers at London Business School have found that pharma advertisements containing a longer “laundry list” of potential side effects were rated as less risky, compared to those that share just a few, more serious reactions.

This effect is known as argument dilution, and according to the researchers, it has a very real effect on consumers’ ability to judge how severe the presented side effects of a drug really are. The researchers published their findings in the journal, Nature.

In the study, participants were shown two DTC drug ads, one of which had been altered to include only the most serious side effects. These ads were for popular drugs, including Sunovion’s sleep aid Lunesta and Eli Lilly’s depression drug Cymbalta, and were presented in a variety of forms such as print and audio.

If all of the potential side effects were presented to consumers, they were more likely to rate the drug as less risky. This was compared to edited ads which did not contain the less-serious side effects – such as dry mouth and headaches – which study participants were less likely to rate as risky.

Furthermore, consumers reported that they were more attracted to drugs whose ads relayed all possible side effects, highlighting the effects of argument dilution. Over 3,000 US consumers were included in the study.

“The results pose a bit of an ethical conundrum,” said Niro Sivanathan, Associate Professor of Organisational Behaviour at London Business School. “On one hand, the FDA wants transparency and for people to have access to the full risk factors. But if you hold back on the risk information, one could argue you’re not giving all the necessary information.”

Sivanathan suggests that the argument dilution effect could be minimized simply by altering how the side effect information is relayed to consumers. They found that emphasizing the more serious side effects by highlighting them in red text, while simultaneously playing down the mild reactions by leaving them in plain text, was effective at conveying the important risk information to consumers in the study.

“There is no right answer here, and there are a lot of gray areas,” said Sivanathan. “We most certainly are not coming down to say do this or do that, but rather highlighting that, in its current state, listing all the side effects reduces people’s risk assessment and, in fact, increases the marketability of these drugs. The FDA regulations have, in fact, helped these direct-to-consumer ads sell more drugs.”

The US Food and Drug Administration (FDA) currently requires drugmakers to list all side effects of a drug, regardless of how often they’ve been reported. However, an FDA-led study published earlier this year found that consumers were better able to recall risk information when the side effects were presented more succinctly, suggesting the regulator is interested in exploring this issue. Still, it’s unclear what effect this will have on future policy for pharmaceutical marketing.