Beer advertisements may make you thirsty, or you might sign up for P90X workouts after watching an infomercial... but can TV commercials improve your drugs? New research in the journal PNAS reveals that Claritin becomes a more effective weapon against allergic reactions after users watch its ads.

Only two countries in the world — the U.S. and New Zealand — allow direct-to-consumer (DTC) promotions for drugs via mass media (TV, print, radio). In the U.S. alone, $4.8 billion spent on marketing campaigns by pharmaceutical companies, with the merits and negative consequences being the major subject of debate. One recent survey reported that nearly 3,000 research studies had been conducted to measure the impact of DTC marketing.

"Some of these studies claim that direct-to-consumer advertising elevates demand for prescription drugs by inducing patients to request advertised medications from their physicians," wrote the researchers — a doctor, a law professor, and an economist from the University of Chicago.

"Our study suggests that advertising may have other important effects on public health."

They invited 170 people without allergies to watch commercials for Claritin or Zyrtec, which are two popular, over-the-counter antihistamine medications. Before watching the ads, each subject was asked to take a 10 mg dose of Claritin.

"The Zyrtec advertisement stated that Zyrtec 'starts working two hours faster than Claritin,'" according to the report.

After seeing the commercials, each individual was then given a "histamine challenge" — an arm was swabbed with the compound — which triggers an allergic reaction in everyone, even if they don't have a history of allergies.

Two hour later, less severe allergic reactions were recorded when people watched ads that supported Claritin. This benefit strongly correlated with a change in people's opinions on the Claritin, which was surveyed before and after the drug was taken.

This argues for the existence of a quasi-placebo effect with this market campaign. A placebo effect is the phenomenon where merely thinking about taking a remedy for a disease can cure symptoms of the disorder.

"Television advertising may influence the efficacy of a branded drug once it is consumed," concluded the authors. "Our results suggest that a commercial phenomenon, television advertising, may be an important trigger for psychologically mediated physiological effects of a drug."

However, this effect may not apply to everyone.

In a similar sized experiment in subjects with allergies, no connection was seen between allergic response and ad-influenced perceptions about Claritin.

It is possible that people with a long history of allergies are less swayed by this placebo effect, but according to the authors, new allergy sufferers may witness a drug efficacy boost after watching the ads. This finding may interest drug companies that are looking for new ways to attract customers.

"Our results are likely to apply to patients who were recently diagnosed with allergies or to patients who are particularly susceptible to advertisements. A recent study reports that new users account for as many as 15% of all patients using antihistamines," wrote the researchers.

Although this is an attractive premise for ad companies, they may want to see more research before changing their policy, as several questions remain. Are symptoms — sneezing, runny nose, coughing — improved by ads? Do negative commercials have the same effect as positive ads? And the big one: why and how does the 'power of suggestion' in the mind change how the body reacts?

Source: Kamenica E, Naclerio R, Malanic A. Advertisements impact the physiological efficacy of a branded drug. PNAS. 2013.