Side Effects In Drug Ads Don’t Add Up

–The long recitation of all possible side effects dilutes the perception of risk.

One of the most perplexing aspects of the ubiquitous direct to consumer (DTC) prescription drug advertisements is the seemingly endless recitation of side effects in drug ads. The list is, alternatively, horrifying, boring, concerning, and silly. It is reasonable to wonder how these ads, with their interminable list of side effects, lead to greater sales of the drugs they promote.

Now a paper published in Nature Human Behavior shows that the long recitation of side effects actually serves to diminish or blunt negative perceptions of the drugs.

The United States and New Zealand are the only countries to permit DTC advertising of prescription drugs. DTC is now a $4.5 billion industry. The long list of side effects is mandatory, since the FDA requires ads to include an assessment of both the benefits and risks of the products, including all possible side effects.

In their paper Niro Sivanathan and Hemant Kakkars (London Business School) set out to show that “despite the FDA’s good intentions to inform (vulnerable) consumers of the potential risk and side effects of pharmaceutical drugs, over the years these regulated advertisements might have produced the unintended outcome of dampening one’s assessment of the side effects and in the process further promoted the benefits and attractiveness of the drugs.”

They contend that this unintended effect is an example of the “argument dilution effect,” in which “information of little value and consequence for outcome prediction… dilutes the value and importance” of information about more serious consequences.

“We contend that the FDA, in regulating DTC advertisements to list side effects that range from the serious (such as stroke and thoughts of suicide) to those less serious (such as dry mouth and headache), have diluted consumers’ judgements of the overall severity of the drug’s side effects. Thus, the current practice of listing both severe and frequent but minor side effects, paradoxically plays down the risk factors in assessing the suitability of the drug, and in turn increases its attractiveness.”

In a series of studies the authors randomized typical US consumers to listen to or read different versions of real and imaginary pharmaceutical ads. The ads differed in the amount of information included about side effects. People who saw or read the full version of the ads had a more benign view of the side effect profile than people who saw the shorter version of the ads with only the most serious side effects listed. “The presence of minor side effects significantly diluted participants’ severity judgements,” the authors wrote.

In one study all the subjects were exposed to a full list of side effects, but in one group the major side effects were presented in larger bold red text. This also increased the perception of risk. The authors said that this method might be attractive because it has the virtue of continuing to provide complete information to consumers while also structuring the information in a way that improves the perception of risk.

In an accompanying viewpoint, Brian Zikmund-Fisher (University of Michigan) writes that “at a minimum,” the study findings suggest “that medication risk communications… need to separate and potentially highlight information about severe adverse events versus less-severe risks.”

Drug Ads Are Like Drugs

My own view is that drug ads are themselves like drugs. Have you heard about ASMR, which stands for Autonomous Sensory Meridian Response? defines ASMR as “a calming, pleasurable feeling often accompanied by a tingling sensation. This tingle is said to originate in a person’s head and spread to the spine (and sometimes the limbs) in response to stimulation. The stimuli that trigger ASMR vary from person to person. Some of the most common ones include whispers, white noise, lip smacking, having a person’s complete attention (as in having one’s hair cut by a hairdresser), and more.”

ASMR videos are wildly popular on YouTube, racking up hundreds of millions of views. There’s no solid science behind ASMR, but its popularity suggests that something real is going on, at least in those who appear to be susceptible to the videos.

My suspicion is that the side effect portion of drug ads on television relies on the techniques of ASMR to lull or practically hypnotize viewers into a state of benign, uncritical acceptance. It would not surprise me at all to learn that the advertising agencies that produce the drug ads are consciously using ASMR videos as a model.



  1. It reminds of the cigarette warning labels. The tobacco companies didn’t fight them too hard. They knew the warnings wouldn’t scare off many of their customers (because they had a far better understanding of customer behavior than either regulators or public health experts)… and because the labels provided a helpful legal argument they then used to fend off lawsuits from smokers and survivors.

    Never underestimate the ability of expert marketers to know (and exploit) the difference between how regulators, health officials, politicians and members of the general public expect people to respond to messages… and how real people actually do respond.

    The Nobel prize for Economics just recognized work on the predictable irrationality of people. DTC ad warning responses are a related case.

  2. And then there’s the question of how best to warn about potential interactions with other drugs.

  3. What is the incidence of each of those side effects?
    If I know that the incidence of horrible side effects is minimal and that the somewhat inconvenient side effects are more common, I would have a very different view of my risks than if it were the other way around.
    As it is, listing all possible side effects without incidence percentages is meaningless.

    • “As it is, listing all possible side effects without incidence percentages is meaningless.” In Britain I’m used to seeing side effects listed with their frequencies described – 1 in 10, 1 in 100, 1 in 1000, and such. Don’t you do this in the US?

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